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Full text of "Nature and science"

r T • 











FOR THE PEOPLE 

FOR EDVCATION 

FOR SCIENCE 






LIBRARY 

OF 

THE AMERICAN MUSEUM 

OF 

NATURAL HISTORY 





nature and science "****»«* 



rEACHER'S EDITION 

'OL. 6 NO. 1 / SEPTEMBER 16, 1968 / SECTION 1 OF TWO SECTIONS 

OPYRIGHT © 1968 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 

Nature and Science and . . . 

i 

. . .Your Pupils . . .You 



■ Do your pupils think of nature as 
the world of birds and bees and flowers 
and trees— a "special" world that they 
zan enter or leave at will? Do they 
think of science as men in white coats 
—modern alchemists devoted to mak- 
ing "new and better" things? 

A great many people still think of 
nature and science in such erroneous 
ways as these, at a time when it is be- 
aming apparent that the survival of 
nan and many other living things de- 
Dends on how well we understand the 
processes of nature— and on what we 
lo with our understanding. 

If your pupils have been reading 
Wature and Science, they know that 
he birds and bees and flowers and 
rees are all part of nature— but so are 
he earth and its seas of water and air, 
jpace with its planets and stars, and 
■very living thing, including your 
pupils themselves. 

They know that everything in nature 

s constantly changing; they know 

omething about the forces that cause 

(Continued on page 4T) 



■ There is more to Nature and Science 
than meets your pupils' eyes — this 
Teacher's Edition, for example. 

It brings you additional background 
information about the subjects and 
concepts of some of the articles in the 
students' edition; it suggests topics for 
class discussion that will help your pu- 
pils relate what they learn to their own 
lives; it suggests classroom activities 
that will reinforce the understanding 
your pupils get from reading an arti- 
cle; and it recommends references for 
further information you might want. 

For your convenience, the Teacher's 
Edition also provides the answers to 
the Brain-Boosters in the accom- 
panying students' edition, and suggests 
ways to help your pupils find the solu- 
tions for themselves. 

Your pupils will get a lot out of 
Nature and Science without your help. 
But by using some of the suggestions 
in this Teacher's Edition, you can 
greatly enhance the value of Nature 
and Science to your pupils and to your- 
self as a teacher ■ 




3RNELLALUMNI NEWS 



GORDON HICKS 



UJolves in our family 



the classroom . . . out-of-doors, Nature and Science shows your pupils how to in- 
stigate nature and its forces in an amazing variety of ways. 



A RTlCLESONPAGE£L 



10 WAYS TEACHERS ARE USING 
NATURE AND SCIENCE 

1. To start children investigating natural 
phenomena on their own in a scien- 
tific manner. 

2. To amplify and update concepts pre- 
sented in texts and to spark lively and 
meaningful class discussions. 

3. To develop children's skills in observ- 
ing, formulating meaningful ques- 
tions, investigating, and evaluating 
their findings. 

4. For homework assignments and for 
classroom reading. 

5. As a source of ideas for themes, small 
group investigations and reports, sci- 
ence club projects, science fair exhib- 
its, weekend and vacation science 
projects. 

6. For assignments that relate science 
to other subjects such as English, 
history, social studies, and the visual 
arts. 

7. To stimulate interest of slow readers 
and for remedial reading instruction. 

8. As extra educational nourishment for 
the fast learner. 

9. As a springboard for field trips to 
zoos, museums, botanical gardens, a 
neighboring park, a nearby stream or 
woods. 

10. As a "how to" guide for making, ac- 
quiring, and maintaining simple class- 
room "hardware" such as terrariums, 
aquariums, balances, sundials, home- 
made microscopes, bird feeders, etc. 

Although many teachers use NATURE 
AND SCIENCE in conjunction with a text- 
book, several hundred teachers have 
discovered they can use NATURE AND 
SCIENCE as the main "text" for an 
informal yet effective science course 
throughout the year. 



USING THIS 

ISSUE OF 

NATURE AND SCIENCE 

IN YOUR 

CLASSROOM 



Wolves in Our Family 

In past issues of N&S, Dave Mech, 
a biologist at Macalester College in 
Minnesota, has pointed out the role of 
wolves as predators of large mammals 
such as moose, deer, and caribou. He 
has also described how the wolf's 
"bad" image has continued despite 
evidence of the animal's good effects 
in nature. 

Through destruction of habitat and 
by hunting, trapping, and poisoning, 
wolves have been wiped out in most of 
the United States. Lately there have 
been suggestions that wolves be re- 
established in areas such as Yellow- 
stone National Park. The park has too 
many elk; wolves would probably help 
bring the elk herd into a better balance 
with its food supply. 

Studies of wolves in their natural 
surroundings have shown that these 
predators have a beneficial effect on 
prey species. Wolves (and other pred- 



NATURE AND SCIENCE is published for The American 
Museum of Natural History by The Natural History 
Press, a division of Doubleday & Company, Inc., fort- 
nightly September, October, December through March; 
monthly November, April, May, July (special issue). 
Second Class postage paid at Garden City, N.Y. and at 
additional office. Copyright © 1968 The American 
Museum of Natural History. All Rights Reserved. Printed 
in U.S.A. Editorial Office: The American Museum of 
Natural History, Central Park West at 79th Street, 
New York, N.Y. 10024. 

SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester 
per pupil, $1.95 per school year (16 issues) in quanti- 
ties of 10 or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's 
edition $5.50 per school year. Single subscription per 
calendar year (17 issues) $3.75, two years $6. Single 
copy 30 cents. In CANADA $1.25 per semester per 
pupil, $2.15 per school year in quantities of 10 or more 
subscriptions to the same address. Teacher's Edition 
$6.30 per school year. Single subscriptions per cal- 
endar year $4.25, two years $7. ADDRESS SUBSCRIP- 
TION correspondence to: NATURE AND SCIENCE, The 
Natural History Press, Garden City, N.Y. 11530. Send 
notice of undelivered copies on Form 3579 to: NATURE 
AND SCIENCE, The Natural History Press, Garden City, 
N.Y. 11530. 



ators) tend to catch the individuals in 
a population that are least fit, espe- 
cially those that are diseased or old. 

Reintroducing wolves in certain na- 
tional parks and other wild areas would 
help prevent the threatened extinction 
of this valuable species in the original 
48 states. It would help also to ensure 
that scientists could go on learning 
about the complex social life of wolves. 

Topics for Class Discussion 

• What did Dr. Mech's discoveries 
tell him about the behavior of all 
wolves? Very little. As the author 
points out, he could not be sure that 
all wolves would act as his did. They 
were raised in unnatural conditions. 
Also, scientists are cautious not to 
generalize from observations of a few 
individuals. 

• Why did the wolf pups fight with 
each other? This behavior led to the 
establishment of an order of domi- 
nance. Your pupils may be able to 
name other kinds of animals that have 
a similar social system. One of the 
best-known examples is the "peck or- 
der" of chickens. 

• Why did Lightning become un- 
friendly toward strangers? Evidence 
from Mech and other observers sug- 
gests that wolves form their lifetime 
social ties during the first few months 
of life. After that, they are wary of 
strange wolves. This behavior helps 
unite the pack and reduces conflicts 
between packs so that each group has 
its own territory in which to hunt. 

For Your Reading 

For further information about wolf 
behavior, see the article "The Social 
Organization of Wolves," in the May 
1968 issue of Natural History maga- 
zine. 

Dating the Past 

Your pupils will probably agree that 
we have to know how things have 
changed in the past if we are to make 
reasonable predictions about how they 
are likely to change in the future. We 
can only find out what happened in 
the past, however, by investigating the 
remains of past events that are left in 
our present-day world. 

To learn very much from remains, 






though, we have to be able to order 
them in time— find out which came 
first, second, third, and so on (relative 
dating), and if possible, when each one 
appeared (absolute dating). 

Topics for Class Discussion 

• What part does dating play in the 
"Ice Age" mystery (see page 12).' 
Relative dating of layers of glacial 
drift disclosed that ice sheets advanced 
and retreated four times in the past 
million or so years. If these advances 
can be dated absolutely, it may help 
us discover what caused them. 

• Can you think of some different 
kinds of remains, what clues they might 
give to past events, and how they might 
be dated? Tracks in sand show what 
kind of animal or machine was there 
recently— probably since the last high 
tide or high wind. 

Objects in a refuse heap— packages, 
clothing, tools, toys, and so on— might 
show what kinds of things people used 
in past years. If the heap has not been 
stirred up, an object's position in the 
heap suggests its relative age. A date 
printed or stamped on an object sug- 
gests the absolute age of objects at the 
same level in the heap. 

• Can you think of some problems 
that might arise in dating by the meth- 
ods described in the chart? Rock lay- 
ers may have been broken, raised, or 
lowered by earthquakes, or worn com- 
pletely away by erosion in some places. 
No tree of the same species grown un- 
der the same weather conditions and 

(Continued on page 3T) 



string—* 


FUTURE 


^^ 


PRESENT s' 


cardboard ^"^ 

inked "breaks"— »- 


PAST 



2T 



Make or draw this "model" of time to help 
your pupils visualize time as a line extend- 
ing (we don't know how far) into the past 
and future, and the present as a "thin 
slice" of time in which we live. We can 
only find out about the past by studying 
what is left of it in the present 

NATURE AND St lENt I 



TZM&ER 16, 19S8 



Can you measure time 
without a clock? 

see page 15 

HOW LONG 
IS A MINUTE? 




nature and science 

VOL. 6 NO. 1 / SEPTEMBER 16, 1968 



CONTENTS 

2 Wolves in Our Family, by Dave Mech 
6 Climbing Water, by Robert Gardner 
8 Dating the Past 

10 Putting a Frog "to Sleep," 

by Anthony Joseph 

1 1 Brain-Boosters, by David Webster 

12 Is the "Great Ice Age" Over?, 

by Diane Sherman 

15 How Long Is a Minute? 

16 What's New?, by Roger George 

PICTURE CREDITS: Cover by Laurence Pringle; p.3, top by Dave Mech, 
bottom by Charles Bjorgen, from Minneapolis Star; pp. 4-5, top left by Charles 
Bjorgen. from Minneapolis Star, others by Laurence Pringle; pp. 6-12, 14-16, 
drawings by Graphic Arts Department, The American Museum of Natural 
History; p. 11, photo by David Webster; p.12, courtesy of U.S. Army Cold Re- 
gions Research and Engineering Laboratory; p. 13, by Christopher Schuberth; 
p. 16, photo by Newsday, Long Island. 



PUBLISHED FOR 

THE AMERICAN MUSEUM OF NATURAL HISTORY 

BY THE NATURAL HISTORY PRESS 

A DIVISION OF DOUBLEDAY & COMPANY, INC. 

editor-in-chief Franklyn K. Lauden; executive editor Laurence P. 
Pringle; associate editor R. J. Lefkowitz; assistant editor Mar- 
garet E. Bailey; editorial assistant Alison Newhouse; art director 
Joseph M. Sedacca; associate art director Donald B. Clausen 
consulting editor Roy A. Gallant 

publisher James K. Page, Jr.; circulation director J. D. Broderick 
promotion director Elizabeth Connor 
subscription service Frank Burkholder 

NATIONAL BOARD OF EDITORS 

PAUL F. BRANDWEIN, CHAIRMAN, Dir. of Research, Center for Study of 
Instruction in the Sciences and Social Sciences, Harcourt, Brace & World, Inc. 
J. MYRON ATKIN, Co-Dir., Elementary-School Science Project, University of 
Illinois. THOMAS G. AYLESWORTH, Editor, Books for Young Readers, 
Doubleday & Company, Inc. DONALD BARR, Headmaster, The Dalton 
Schools, New York City. RAYMOND E. BARRETT, Dir. of Education, Oregon 
Museum of Science and Industry. MARY BLATT HARBECK, Science Teach- 
ing Center, University of Maryland. ELIZABETH HONE, Prof, of Education, 
San Fernando (Calif.) State College. GERARD PIEL, Publisher, Scientific 
American. SAMUEL SCHENBERG, Dir. of Science, New York City Board of 
Education. WILLIAM P. SCHREINER, Coord, of Science, Parma (Ohio) City 
Schools. VIRGINIA SORENSON, Elementary Science Consultant, Dallas In- 
dependent School System. DAVID WEBSTER, Staff Teacher, Elementary 
Science Study, Educational Development Center, Newton, Mass. • REPRE- 
SENTING THE AMERICAN MUSEUM OF NATURAL HISTORY: FRANK- 
LYN M. BRANLEY, Chmn., The American Museum-Hayden Planetarium. 
RICHARD S. CASEBEER, Chmn., Dept. of Education. THOMAS D. NICH- 
OLSON, Asst. Dir., AMNH. GORDON R. REEKIE, Chmn., Dept. of Exhibi- 
tion and Graphic Arts. DONN E. ROSEN, Chmn., Dept. of Ichthyology. 
HARRY L. SHAPIRO, Curator of Physical Anthropology. 

NATURE AND SCIENCE is published for The American Museum of Natural History by 
The Natural History Press, a division of Doubleday & Company, Inc., fortnightly 
September, October, December through March; monthly November, April, May, July 
(special issue). Second Class postage paid at Garden City, N.Y. and at additional 
office. Copyright © 1968 The American Museum of Natural History. All Rights Re- 
served. Printed in U.S.A. Editorial Office: The American Museum of Natural History, 
Central Park West at 79th Street, New York, N.Y. 10024. 

SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester per pupil, $1.95 per school 
year (16 issues) in quantities of 10 or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's edition $5.50 per school year. 
Single subscription per calendar year (17 issues) $3.75, two years $6. Single copy 30 
cents. In CANADA $1.25 per semester per pupil, $2.15 per school year in quantities 
of 10 or more subscriptions to the same address. Teacher's Edition $6.30 per school 
year. Single subscriptions per calendar year $4.25, two years $7. ADDRESS SUB- 
SCRIPTION correspondence to: NATURE AND SCIENCE, The Natural History Press, 
Garden City, N.Y. 11530. Send notice of undelivered copies on Form 3579 to: 
NATURE AND SCIENCE, The Natural History Press, Garden City, N.Y. 11530. 



I wanted to learn more about 
the behavior of wolves, so 
I was delighted when 
we had a chance to raise . . . 



1 

Wd 






■ I never thought I'd be a member of a wolf pack. 

But I was. It wasn't exactly like a wild wolf pack, for 
besides two wolves, it included four children, my wife 
and me, and a dog. Still, it was enough like a real pack so 
that I was able to learn a few things about the early family 
life of wolves. And that's just what I wanted to do. 

It all began in May 1967 when I got a call from the di- 
rector of the zoo near our home in Minnesota. 

"How'd you like to raise a couple of wolf pups?" he 
asked. 

I had studied wolves in the wild and was writing a book 
about them. Raising some pups would teach me more 
about wolves, and this would help me with the book. 
"That would be great," I replied. Then we began to get 
ready for our new guests, which we decided to name 
"Thunder" and "Lightning." 

Learning from the Pups 

The first things we needed were baby bottles, for the 
pups were still nursing milk from their mother when we 
got them. They were only 10 days old. About all they 
could do was whine, move their heads from side to side, 
and suck strongly on a nipple. They could neither see nor 
hear. If they had been born in the wild, they would have 
stayed at the bottom of their den in the ground for another 
10 days. 

From the beginning, of course, I made notes about 
everything the pups did, and how they grew and changed. 
I realized that just raising two young wolves was not going 
to teach me all there was to know about wolf pups. But I 
did expect to gain two important things from this study. 

First, I would find out what some wolf pups are capable 
of. I couldn't be sure that all wolves would act the same 
way as mine. Nevertheless, I could learn what wolf pups 
can do and how they can grow. 

Second, raising a pair of wolves would give me ideas 
and questions to investigate. I knew that as I watched 
the pups grow and change, all sorts of new thoughts would 
come to me. If they seemed important enough, I could 
raise more pups some day and test my ideas further. This 
is the way many scientists work. 

NATURE AND SCIENCE 



M aOltlNUt MUVtIN I UKt 



**.«. 




in our 
family 



Thunder and Lightning grew and changed rapidly. At 
rst all they did was drink and sleep, but within three days 
fter we got them, their eyes opened. Both wolves then 
:arted to walk and tumble about. When they were three 
'eeks old, they began to hear, and soon they were running 
rid playing. Each already had several teeth. In the wild, 
le pups would just be venturing out to the mouth of their 
en for the first time. 

At this stage, the wolf pups looked like roly-poly teddy 
ears (see photo). They were soft and furry, their noses 
'ere "pugged," and their ears were floppy. Our four 
hildren, ages 3 to 7, had completely fallen in love with 
lem, and our dog had adopted them as if they were her 
wn. It looked as though we were going to have one big 
appy pack. 

Vho Is the Boss? 

Then suddenly a strange thing happened. At 27 days 
f age, Thunder and Lightning began fighting. After each 
ceding, the pups would rush toward each other. One 
iou\d put its paws over the neck of the other and force 
: down. Then each pup would try to bite and chew the 
ther's back as hard as it could. 

Usually we stopped these fights. However, one time I let 
lem continue— just to see what would happen. The pups 
DUght for 10 or 15 minutes, and it seemed to me that they 
light die from exhaustion. The fur on the back of each 
'olf was ragged from the chewing, and there was blood 
[lowing. I separated them for the night. 

(Continued on the next page) 

September 16, 1968 



by Dave Mech 



The wolves had floppy ears and "pugged" noses when just a few 
weeks old. Later they played rough-and-tumble games with 
the Mech children. When the photo below was taken, Lightning 
weighed 60 pounds and had sharp adult teeth. She never bit 
any of the children. The photo on the cover shows Lightning 
greeting the author's wife, Betty Ann Mech. 




Wolves in Our Family (continued) 

The next day the pups again tried to get to each other 
and fight. Our whole family spent the day keeping them 
apart. Lightning, the female, often attacked Thunder, even 
though Lightning was smaller and usually ended up get- 
ing the worst of the battle. 

After another day of trying to keep the pups apart, we 
decided that our only solution was to give one of them back 
to the zoo. The next day, when the pups were 30 days old, 
we got ready to return one of them. First, however, I put 
them together for one last time, to take their pictures. 

Thunder and Lightning rushed right to each other and 
began fighting in their usual way. But this time, something 
unusual happened. When Thunder pressed Lightning to 
the ground, she did not fight back. Instead she rolled over 
on her back and whined. At the same time, Thunder 
stopped his attack and stood stiffly over her with his tail 
straight up in the air. 

Suddenly, I knew what had happened. The pups had 
finally decided which one was boss. In any wolf pack, 
each wolf knows just how many others he can boss, or 
dominate, and which members of the pack can boss him. 
The leader of the pack can dominate any other wolf in 
the pack. The one at the bottom of the "ladder" can be 
bossed by all the other wolves in the pack. 

This order of dominance leaves little room for fighting, 
for each wolf knows its own place. If several wolves come 
upon a piece of meat too small to share, for example, the 
animal with the highest rank in the group automatically 
gets to eat it. 

But somehow there has to be a way that each wolf learns 
just what rank it has in a pack. Usually young wolves find 
this out by playfully fighting with their packmates. As the 
pups wrestle, chase, and play other games with each other, 
they eventually learn which wolves they can beat and which 
ones can beat them. But this is all done through play. 

That's why the actions of Thunder and Lightning were 
so surprising. Their fighting wasn't a bit playful; it was 
deadly serious. Still, it finally taught each animal just 
which one was boss. As soon as I saw Thunder stand over 
Lightning with his tail straight up, I could see that their 
problem— and ours— was solved. From that moment on 
there were no more fights between our pups. Every time 
they met after that, they did the same thing: Thunder 
showed that he was dominant, and Lightning showed that 
she was subordinate, and they got along perfectly. 

The pups that had been born with Thunder and Light- 
ning and were being raised by their parents in the zoo 
did not fight like ours. I realized that what our pups did 
was very unusual and probably had something to do with 
their being raised without adult wolves around. The very 
fact that this was unusual, however, may someday help us 




find out much more about how the order of dominance 
forms in a wolf pack. Often scientists learn a great deal 
from seeing how animals act under abnormal conditions. 

Games Wolves Play 

Once our pups settled things between them, we had no 
more trouble raising them. They began eating meat when 
only a few weeks old, and grew and changed rapidly. At 
about 50 days of age, they started howling whenever they 
heard fire sirens. Their fur grew much longer, and the 
animals very much disliked heat. They always lay in the 
shade and often dug shallow beds in the cool soil. This 
probably explains why wolves in the wild usually travel 
and hunt at night during the summer— to escape the heat. 

Gradually the pups became more and more attached to 
our whole family, including the dog. They followed every- 
body around the backyard, and played a lot. 

From the first few weeks of age the pups would grab 
fuzzy things such as slippers and would growl, and shake 
and chew them. When they grew older, the wolves would 
take any newspaper or cardboard box they could find and 
shred it into little strips. One day I put on some old ragged 



NATURE AND SCIENCE 




clothes and wrestled with the pups. As I rolled around the 
ground with them, they grabbed and tugged at my clothing 
and began peeling shreds of it off me. This reminded me 
very much of scenes I had seen in the wild where a pack 
of wolves had pulled a moose down and were tugging and 
ripping at it. 

That's when I realized what these games were. In the 
wild, this kind of play would have helped the pups practice 
the patterns that they would use in killing and eating their 
prey. Instead of peeling cardboard boxes, they would be 
stripping fur or feathers off dead animals that their parents 
brought them. 

It began to occur to me that wolves really aren't born 
with a "killing instinct." Instead, they seem to have certain 
behavior patterns that when practiced and put together 
during the usual life of wolves would lead to killing. Maybe 
someday I could raise some wolves without ever letting 
them practice these patterns. Then, when adults, would 
they ever learn to hunt and kill? 

Another thing that our wolves did that looked like play 
was really a kind of greeting. Whenever anyone ap- 
proached a pup, the animal would leap at his mouth and 

September 16, 1968 



try to nip and lick it. This is just what one wolf does to 
another when they meet. Our children soon learned to 
cover their faces with their arms when the wolves tried 
to greet them. 

These greetings, and other forms of playful contact, 
help wolf pups become attached to each other and to the 
adults in their pack. Such contacts also build similar social 
ties between the adults and the pups. I know that our pups 
really felt attached to our family, and our family to them. 
We realized this especially when Thunder died at the age 
of three and a half months from a disease called distemper. 

No More Friends 

But we still had Lightning. By the time she was four 
months old, she began looking more and more like an 
adult wolf. She weighed 37 pounds, and her feet and head 
were almost as large as those of adult wolves. Her fuzzy 
puppy fur was almost covered by a new coat of long 
gray hairs. She also lost several of her puppy teeth as her 
adult teeth began to come in. 

Along with all those changes, Lightning also began 
acting differently. So far, she had been open and friendly 
to any person or dog who came into the yard. But when 
she was about five months old, Lightning became afraid 
of strangers, both humans and dogs. She also started to 
threaten strange dogs that ventured into neighboring yards. 
With dogs and people whom Lightning knew, however, she 
stayed just as friendly as ever. Other people who have 
raised wolves at home and in zoos have also noticed this 
behavior. 

These changes in the wolf's behavior make me believe 
that wolf pups in the wild form their social ties during the 
first few months of life. In that period about the only 
wolves they meet are members of their own pack. So the 
pups can only form feelings of attachment to those animals. 
By the time the pups start traveling widely enough to meet 
strange wolves, they can no longer make social ties very 
easily. Instead, they become unfriendly or fearful towards 
the strangers. This is probably what keeps each pack 
separate from others in the wild. By staying apart, each 
group of wolves can hunt for food in a different area and 
find enough to eat. 

Of course, it would be very hard to learn these kinds of 
things about wolves by studying them in the wild. This is 
why the study of wolves raised in captivity is so important. 
The wolves in our "pack," Thunder and Lightning, gave 
me many new ideas about wolf behavior that I want to 
investigate further ■ 



H A good book on wolves, illustrated with many black and white 
photos, is: The World of the Wolf, by D. Pimlott and R. Rutter, 
J. B. Lippincott Co., Philadelphia, 1967, $4.95. 



SCIENCEIBH 





With some common kitchen equipment 

you can investigate how liquids 

are "soaked up" in 

certain materials. 



by Robert Gardner 




■ How does a towel "soak up" water, or a blotter "pull up" 
ink? How can you empty a pail of water without pouring? 
Here are some ways to investigate and find answers to 
these questions. Perhaps you will also find some new 
questions of your own that you will want to explore. 

Cut a strip of paper towel or blotter paper about an inch 
wide and a foot or more long. Hang the strip so that one 
end dips into some water colored with a few drops of ink or 
food coloring. You can use some tape to hang the strip 
from a cabinet over the kitchen counter. Or you could 
stick it to a chair if you put the water container on the 
floor. You might even use a cardboard carton to make a 
"water soaker-upper" testing laboratory like the one shown 
on this page. 

Watch what happens after the strip is dipped into the 
water. Leave the strip in the water for several hours, then 
look at it again. What has happened? Try the same thing 
with different kinds of cloth, paper, blotters, string, and 
other materials you think might work. What differences 
do you see? 

Now, repeat the investigation using two paper strips, but 
cover one of the strips with a piece of waxed paper. You 
can seal the edges of the waxed paper together with sticky 
tape. One end of the cover should be open so the paper 
strip can dip into the water (see diagram). Compare how 




the water rises in the covered and uncovered strips. 

Can you explain why you got different results when the 
strip was covered? If not, try this: Wet two paper towels, 
and hang one in the air. Place the other one in a glass jar 
and cover it. Which towel dries faster? Why? Do you see 
now why water rises to different heights in the covered and 
uncovered strips? 

But what causes water to climb up a paper towel, a piece 
of cloth, or a blotter at all? What enables it to "defy" 
gravity this way? 

The Spaces Where Water Climbs 

Tear a piece of paper towel, blotter, or cloth, and look 
at the edge through a strong magnifying lens or a micro- 
scope. You will see many tiny threads, called fibers. These 
fibers are packed together so closely that we usually don't 
notice them. You know that if you dip the material into 
water, the water will seem to "climb up" its fibers. If you 
look carefully with a microscope you can see that the 
water actually "climbs up" the narrow spaces between the 
fibers. 

Does it matter how closely the fibers are packed to- 
gether? It's hard enough to see the small fibers; how can 
you see the tiny spaces between the fibers without a micro- 
scope? Well, you can't, of course, but you don't have to. 
You can find out what water does in narrow spaces by 
doing something that you can see. 

Take two straight-sided drinking glasses and place them 
in a tray of colored water. You can use a pie or cake pan 
as a tray, or you can make one by cutting a milk carton the 




long way (see diagram). Bring the sides of the two glasses 
very close together. As you do so, watch what happens to 
the water level in the narrow space between the glasses. 

If you can get two pieces of flat glass, you can do this 
another way. (Be careful not to cut your fingers on the 
edges of the glass!) Put a thin strip of wood between the 
plates at one end and tape them at both ends to form a thin 

NATURE AND SCIENCE 




wedge-shaped space (see diagram). Can you predict what 
will happen when you place this device in a tray of water? 

What Makes Water Climb? 

The rise of water in a narrow space or tube is called 
capillarity. It is caused by two forces working together. 
One force, called adhesion, attracts water to glass, wood, 
cotton, paper, and certain other substances. The other 
force, called cohesion, attracts water to water, helping 
to hold a portion of water together. 

When water is in, say, a narrow glass tube, adhesion 
makes the water pile up higher next to the glass than at 
the center of the tube. You can see this by looking at the 




surface of the water in a drinking glass (see diagram). 
Cohesion makes the rising water pull some more water up 
with it, and then adhesion makes the water next to the 
glass rise still farther. The water will continue to climb 
until the forces that pull the water up the tube are equal to 
the force of gravity that tends to pull the water down ■ 



PROJECT 



A man once thought he could use capillarity to build 
a perpetual motion machine. He built a device like 
the one shown below. Will it work? 



GLASS 

CAPILLARY 

TUBE 







You don't need the tiny bent capillary tube that is 
shown in the diagram to find out if it will work. You 
can use the many tiny "capillary tubes" in a paper 
towel. As you have found, the water in a single strip 
of paper toweling evaporates quite fast, so you had 
better fold a paper towel a number of times to reduce 
the amount of water exposed to the air. You can check 
to see if the perpetual motion machine will work by 
arranging the towel as shown in Diagram A. To speed 
things up you might wet the towel before dipping one 
end in the water. 





PAPER 
TOWEL 



u 



What will happen if you let the towel hang over the 
edge of the tray so that the end of the towel is below 
the level of the water in the tray, as in Diagram B? 
What can you do to make the water run out faster? 
How high must you raise the end of the towel to make 
the water stop running? 

Can you explain why the perpetual motion machine 
didn't work? 



r. 



INVESTIGATIONS 



• Do you think that some liquids are more strongly at- 
tracted to paper fibers than other liquids? Try dipping 
strips of paper towel, all the same size and shape, into 
different liquids— soapy water, cooking oil, salt water, 
rubbing alcohol, and water. Do all the liquids rise to the 
same height? Might the results be different if each strip 
of towel were shielded by a wax paper tube? Why? 

• Put some water drops on glass, waxed paper, alumi- 
num foil, formica, and so on. Can you guess from the 
shapes of the drops which of these materials attract 



water more strongly? Do you think water would rise 
higher in a capillary tube made of glass or one the same 
size made of wax? (You might use some wax paper and 
two straight-sided drinking glasses to investigate that 
question.) 

• Does the width of a strip of paper towel affect the 
height to which a liquid rises through it? To find out, 
you might test strips of paper towel or blotting paper 
of different widths (say from V4 inch to 3 inches) in 
colored water. 



September 16, 1968 



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■ If you visit a pond or stream today, you'll find it alive 
with animals such as dragonflies, blackbirds, and frogs. 
But the shortening days of autumn will trigger many 
changes. Within a few weeks, in the northern parts of 
North America the dragonflies will be dead, the blackbirds 
will have migrated south, and the frogs will have burrowed 
into the mud at the bottom of their ponds. 
10 



Each kind of animal meets the cold, bare winter in 
different ways. This article tells how you can investigate 
the way a frog is adapted to survive the winter. For this 
investigation you will need at least one live frog. You can 
probably catch one from a pond, or buy one from a pet 
shop. You'll also need a one-quart wide-mouthed jar, 
enough gravel or mud to fill the jar about two inches deep, 
a cake pan, some water, ice cubes, and a thermometer. 

As the Temperature Drops . . . 

Put the gravel into the jar and then fill the jar with 
water to within an inch of the top. Put the frog into the 
water. It will dive to the bottom, then come up to the top. 
Next place the jar in a cake pan. Take the temperature of 
the water and write it down. Continue taking the tempera- 
ture of the water every few minutes as you pack ice cubes 
around the jar and observe the frog's reactions. 

Watch the way the frog behaves as the water cools. 
Look at its throat. Is its pulse quick or slow? Does its 
pulse get faster or slower as the water cools? 

After a while, the frog will go down to the bottom of 
the jar. It may try to push itself down into the gravel. 
Why do you think it is doing this? 

After several minutes the frog may stop moving. Look 
at its throat to see if there is a pulse. Be sure to record 
the temperature of the water at this time. 

Now take the jar out of the pan of ice and put it in a 
warm place. Watch the frog closely as the water warms. 
At what temperature does the animal begin to show signs 
of life? How long does it take for the frog to recover fully 
from the effects of the cold? 



Winter Is on the Way 

This fall, observe the changes in different kinds of 
plants and animals to see how they are adapted to 
the change of seasons. See if different kinds of ani- 
mals change their ways of getting food. You may 
discover that all of the adults of some species die in 
the fall. How does the species survive to another year? 



This investigation will give you an idea of how a frog 
reacts to the cold temperatures of autumn and winter. 
Frogs and many other kinds of animals survive winter by 
going into a deep, death-like sleep called hibernation. 
The heartbeat and pulse of a hibernating animal slow 
down so that they are hardly noticeable. If the animal is 
to live through the winter, however, it must hibernate in a 
place where the temperature around it stays above freez- 
ing. That is why frogs burrow into mud and leaves at the 
bottom of ponds.-ANTHONY Joseph 

NATURE AND SCIENCE 






prepared by DAVID WEBSTER 



FUN WITH 

NUMBERS AND SHAPES 

Arrange the dots into a square 

by changing the position 

of only six dots. 



Submitted by Morgan Merritt, Anchorage, Alaska 



WHAT 

WILL HAPPEN 

ii ■ ■ • 

...the smaller test tube 
is released? 




FOR SCIENCE 
EXPERTS ONLY 

What causes the tops 
of ice cubes to 
bulge upward? 





CAN YOU 
DO IT? 

Stand with your right 
side touching a wall. 
Can you now lift your 
left leg without 
falling over? 



MYST 

What is this truck carrying? 




September 16, 1968 



JUST FOR FUN 

Make a dime dance on top of a pop 

bottle. Put the empty bottle in 

the refrigerator for about half 

an hour; then take it out and 

cover the top of the bottle 

with a dime. Hold the 

bottle in your hands 

until the dime begins 

to jiggle up and 

down. Can you guess 

k why it does? 



GG 








Four times in the past million years 
or so huge ice sheets have crept 
down from the north to cover much 
of North America and Europe. 
Scientists are still trying 
to find out what made this 
happen and whether it _ 

could happen again. 




This photo shows an edge of the huge glacier— up to two 
miles thick in places— that still covers most of Greenland. 



The ice sheet is slowly melting, leaving behind it a pile of 
rock and soil, called a moraine. 



■ Can you picture a huge ice sheet several miles thick, 
extending across a whole continent? If your home is in 
the northern part of the United States, or in Canada, such 
an ice sheet, or continental glacier, may have covered the 
spot where you live (see map). Four separate times in the 
past million and a half years or so ice sheets have covered 
much of North America and Europe for thousands of years 
at a time. They last began to melt back into the Arctic 
regions about 15,000 years ago. 

Will glaciers ever creep down from the north again and 
cover much of the land with mile-high blankets of ice? 
We don't know enough yet to say. Scientists hope to find 
the answer by studying the clues left behind by ice sheets 
of the past. 

Discovering the "Great Ice Age" 

For a long time, the clues that the glaciers left on the 
surface of the earth puzzled people. They were puzzled, 
for example, by huge boulders resting in places where they 
didn't seem to belong. These boulders, called erratics, are 
different in color, texture, and composition from any 
nearby rock. Often the nearest rock like a particular erratic 
is hundreds of miles away. Some people believed that 
erratics had been moved by giants, witches, or devils. 

Then there was the soil in North America and Europe. 
12 



In the southern parts of both continents, the soil is made 
of the same materials as the rock underneath. But in the 
north, the soil is a mixture of gravels, clay, sand, and 
rounded stones of different kinds. This mixture is called 
drift, because people once thought it had drifted over 
Europe during the flood of Noah's time, described in the 
Bible. But no one could figure out how water could have 
made striations— the long, straight, parallel scratches some- 
times found on very hard rocks in northern Europe and 
America. 

In 1821, a Swiss engineer named Ignaz Venetz sug- 




On this map you can 

see how much of North 

America was covered 

by ice sometime in 

the past million years. 

The arrows show the 

directions in which 

the glaciers spread out. 

NATURE AND SC II \< I 



gested that Europe might once have been covered by a 
huge glacier. He had watched mountain glaciers near 
his town and seen how they carried rocks (erratics) down 
into the valleys. He saw how glaciers left piles of stones 
and rubble (drift) behind when they melted back each 
summer. He had noticed rocks sticking out of the ice, 
making long, parallel scratches (striations) in rocks at 
the sides of a narrow valley. 

At first people just laughed at Venetz's theory. Then a 
young Swiss named Louis Agassiz became interested. A 
summer studying glaciers in the Alps convinced him that 
there had been huge glaciers in the past, covering thou- 
sands of square miles of land. Gradually, other scientists 
began to accept Agassiz's idea of a "Great Ice Age." 

How Scientists Tracked the Ice Sheets 

Geologists (scientists who study rocks for clues to the 
earth's history) learned to trace the movements of a long- 
ago glacier by the clues it left behind. For example, a 
glacier must have passed over a place where it could pick 
up a particular kind of rock in order to drop "erratic" 
boulders of that kind farther along its trail. Scratches in 
rock show which way the glacier was moving. Moraines, 
which are big piles of drift that were left stranded when 
the glaciers melted, show how far the glaciers came. 

Digging deep into the earth, geologists found layers of 
drift that were separated by layers of soil. This showed 
that glaciers had covered the land and then melted back 
more than once, with long periods in between when plants 
again grew in the soil. The thickness of the different 
layers, and the kinds of fossil plants and animals found in 
them, gave geologists a rough idea of how old the layers 
might be. 

Putting many different kinds of evidence together, geolo- 
gists have discovered that the Pleistocene Epoch, as the 
"Great Ice Age" is called, probably began between one 
and two million years ago. Four times in that period 
glaciers in North America and northern Europe grew for 
thousands upon thousands of years. Each time they formed 
ice sheets that crept southward a few hundred feet a year, 
covering much of the two continents. Once the ice began 
to melt, it retreated far to the north within a few thousand 
years. For thousands of years between these ice sheets, 
the climate was again warm— sometimes even as warm as 
it is today. 

How a Glacier Grows 

Much of the story of the Pleistocene ice sheets has 
been pieced together, but we still don't know what caused 
them. By studying modern glaciers, scientists have learned 
that they form on top of mountains whenever more snow 
falls in winter than melts in summer. When this happens 

September 16, 1968 



year after year, the snow gets deeper and its weight packs 
down the bottom layers and turns them into ice. 

Eventually the pressure of the snow and ice melts the 
ice at the bottom, and the glacier begins to move. It 
spreads slowly outward, carrying loose rocks and soil 
with it, flowing over low hills and around mountains. As 
long as more snow falls each year than melts, the glacier 
keeps growing and spreading. 

Scientists have suggested many ideas to explain the 
advances and retreats of the Pleistocene ice sheets. A few 
years ago, Dr. Maurice Ewing and Dr. William J. Donn, 
geologists at the Lamont Geological Observatory in New 
York, proposed that they were caused by changes in the 
ocean currents. (Continued on the next page) 




J&pMftB* 



The boulder in the top photo is an erratic— a rock that was 
picked up in one place by a moving ice sheet, then left some- 
where else. The parallel grooves, or striations, in the rock 
shown below were made by rocks sticking out of an ice sheet 
that passed over this rock. Both photos were taken in Cen- 
tral Park, in New York City. 





GREENLAND 



NORWAY 



One theory suggests that warm water that flows through the 
shallow opening between Greenland and Norway (Diagram A) 
evaporates and falls as snow that builds up glaciers. When 

Is the "Great Ice Age" Over? (continued) 

Warm water, they said, flows into the Arctic Ocean 
through a narrow, shallow opening between Greenland 
and Norway. This keeps the Arctic Ocean free of ice. As 
ocean water evaporates and then falls on the glaciers as 
snow, the sea level gradually gets lower. When the sea 
level drops below the opening, warm water can no longer 
flow over the land that connects Norway and Greenland. 

With no warm water coming in, the Arctic Ocean gets 
colder, eventually freezing over. When this happens, there 
is no moisture for new snowstorms, and the ice sheet 
begins to melt. Gradually the water released from the 
glacier raises the sea level. Once more the land between 
Greenland and Norway becomes submerged, and warm 
water begins to flow into the Arctic Ocean, slowly melting 
its ice. Then the cycle begins again. 

Still another theory points out that the tilt of the earth's 
axis changes in several ways over long periods of time, 
and so does the shape of the earth's path around the sun. 
At certain times, these changes work together to put the 
earth and the sun in a position that makes the winters 
warmer and the summers cooler— an ideal climate for the 
growth of an ice sheet. 



Changes in the tilt of the 
earth's axis and in the earth's 
path around the sun may help 
cause glaciers to grow at one 
time and melt at another. One 
way the earth's axis gradually 
changes its tilt is shown in 
this diagram. This motion, 
called precession, is com- 
pleted once every 26,000 
years. 



This theory couldn't be tested very well in the past 
because geologists haven't been able to tell just when the 
different advances of the ice sheet took place. Recently, 
though, geologists at Lamont have used new ways of 
dating the layers of material that has been deposited on 
the ocean floors in the past. Their findings seem to show 
that the oceans were at their present levels about 120,000 
years ago and again about 80,000 years ago. Between 
those times, and again sometime in the past 80,000 years, 
14 




EQUATOR 




GREENLAND 



the sea level drops, warm water is cut off from the Arctic 
Ocean (Diagram B). The Arctic Ocean freezes over, and with- 
out moisture for more snow, the glaciers shrink. 

the sea level was much lower— probably because much of 
the sea water was frozen in ice sheets. 

According to Dr. Wallace S. Broecker, a geologist at 
Lamont, the new times suggested for the last two advances 
of the ice sheet were also the two most recent times when 
the earth and sun were in a position to make winters 
warmer and summers cooler. If this was what caused the 
ice sheet to advance each time, Dr. Broecker suggests, 
then ice sheets may again engulf much of North America 
and Europe roughly 80,000 years from now. 

One of these two theories may explain why glacial 
periods alternated with warmer periods during the Pleis- 
tocene. But what started the cycle in the first place? 

What Could Have Cooled the Earth? 

Perhaps the amount of heat sent out by the sun may 
have dropped for long periods in the past; scientists know 
that it varies somewhat over short periods of time. Or 
perhaps part of the sun's heat was blocked from the earth 
by dust clouds in space, or by dust and ash thrown into 
the earth's atmosphere by volcanoes. (So far, though, 
geologists haven't found any traces of the dust or ash in 
rock layers that were deposited at those times.) 

Another possible cause of lower temperatures may be 
a change in the amount of carbon dioxide in the earth's 
atmosphere. This gas helps to slow down the escape of 
heat from the atmosphere into space. Plants need carbon 
dioxide to grow, and some scientists think that at times 
there may have been such a tremendous growth of plant 
life that much of the carbon dioxide may have been re- 
moved from the atmosphere, causing the earth's tempera- 
ture to drop. 

Many scientists believe the "Great Ice Age" was prob- 
ably caused by a combination of small things. A slight 
drop in yearly temperatures could probably help start a 
glacier, and temperatures normally vary a few degrees. 

Most glaciers have grown smaller during the last cen- 
tury. Greenland's ice sheet is melting, and so is Ant- 
arctica's. As the ice returns water to the oceans, the sea 
level is slowly rising. It may be that we are entering a 
warm period that will last for millions of years. Or we 
may be enjoying a warm period before the glaciers come 
again. Someday, perhaps, we will know the answer. In 
the meantime, scientists will keep looking for clues to the 
long-range weather forecast ■ 

NATURE AND SCIENCE 



SCIENCE 



WORKSHOP 





How long 




minute? 



■ Can you guess when one minute has passed? Ten min- 
utes? Half an hour? Does time seem to pass slower or 
faster when you are doing different things? Here's a way 
to test your time-guessing ability and find out some of the 
things that affect it. 

You'll need a clock or a watch with a second hand to 
measure your guesses accurately. (An electric clock is 
best, because it doesn't "tick.") When the second hand 
reaches "12" on the dial, turn away from the clock. When 
you think 60 seconds have passed, turn back and see 
where the second hand is. Was your "guess minute" 
shorter than a "clock minute" or longer? By how many 
seconds? 

Write "Trial 1" on a slip of paper, followed by "-10" 
if your guess was 10 seconds too short, or "+10" if it was 
10 seconds too long. Make several more trials and see 
whether practice improves your time-guessing ability. 

You might try counting seconds— "one, two, three . . .". 
Does that bring your guess closer to a clock minute? Try 
counting "thousand-and-one, thousand-and-two, thou- 
sand- and- three," and so on, instead of just "one, two, 
three." Does that help? If so, can you guess why? 

Try guessing a longer period of time, say five minutes, 
without counting. Start by writing down the exact clock 
time in minutes when the second hand passes "12." When 
you think five minutes have passed, record the clock time 



in minutes and seconds, and figure out how close your 
guess was. Try guessing 10 minutes, or even half an hour. 
Can you guess short periods of time more accurately than 
longer periods? 

Slow Time, Fast Time 

You have probably noticed that when you are waiting 
for time to pass, it seems to creep along rather slowly. 
This is likely to make you guess that five minutes have 
passed in less than five minutes by the clock. If you are 
doing something, time will probably seem to pass faster. 
But how much faster? Try guessing five minutes while 
you read another article in this magazine, while you read 
a page in a dictionary, while you watch a TV show, or 
while you perform a household chore (such as making 
beds or washing dishes). Does your ability to guess time 
change with the kind of thing you are doing during that 
time? Can you explain why? 

Try to think of other things that might affect your 
ability to guess the passing of time. How about music? 
Try guessing five minutes as you listen to music from a 
phonograph or radio. Does lively music seem to make 
time pass faster for you than slow music? Can you guess 
time more accurately on a busy street or in a quiet room? 
In the morning when you get up, or at night when you go 
to bed? 

If you take time to investigate, you may find many dif- 
ferent things that "speed up" or "slow down" the passing 
of time for you ■ 



INVESTIGATION 



Give some friends and members of your family the 
five-minute guessing test. Test one person at a time, 
in the same quiet room, if possible. Try to test each 
person exactly the same way. Have the subject sit 
with his back to you and the clock, and try not to do 
anything that gives him a clue. Keep a record of each 
test on a separate card, as shown below. 

When you have tested a number of people, see 
what you can find out by comparing their test results. 
Did most of them guess short of five minutes? Did 
most of the females guess about the same way? How 
about the males? Did most of the females seem to 
guess more accurately than most of the males? Did 
a person's age seem to affect the way he guessed 
the passing of time? You can probably think of many 
more questions to ask and try to answer by sorting 
and comparing the results of your tests. 



SUBJECT: R.J.L SEX: Male AGE: 22 DATE: Sept. 16, 1968 




START 


END 


GUESS 


ERROR 


Trial 1 


3:35:00 


3:38:50 


3min.50sec. 


-70 sec. 


Trial 2 










Trial 3 











September 16, 1968 



15 





WHAT'S 
NEW 



by 

Roger George 



A leaky roof has led to the first dis- 
covery of a meteorite in the United 
States since 1961. At a warehouse in 
Denver, Colorado, workers were look- 
ing for the cause of a leak in the ceiling. 
They found a small hole in the roof, and 
just below it, a dull black, rounded stone 
about the size of a child's fist. Experts 
identified the stone as a meteorite. 

As a meteoroid falls through the 
earth's atmosphere, friction heats it to 
temperatures of about 4,000°F. (The 
streak of light that you may see is called 
a meteor.) Most meteoroids burn up 
completely, but sometimes a part of a 
meteoroid may fall to the earth as a 
meteorite. If the Denver meteorite had 
fallen just a few yards away from the 
warehouse, it would have landed in a 
vacant lot and might never have been 
discovered among ordinary rocks there. 

If smokestacks blew smoke rings, 

air pollution could be reduced, says Dr. 
Timothy Fohl of the Massachusetts In- 
stitute of Technology, in Cambridge. 
Smoke blown in rings from factory 
stacks would travel much higher than 
smoke released in the usual way. And 
the higher the smoke rises before it 
starts to spread out in the air, the less air 
pollution there will be at the earth's 
surface. Dr. Fohl suggests that a device 
could be installed in a smokestack that 
would shoot smoke rings 15,000 feet in- 
to the atmosphere. 

Smoke damage and air pollution are 
alarming problems in the United States, 
especially around cities (see photo). 
Smoke is harmful to our throats, noses, 
and lungs. It also poisons plants. Clean- 
ing up from smoke damage alone costs 
Americans billions of dollars a year. 

16 



Hit over the head with a heavy 
club, Dr. Robert F. Cade hardly blinked. 
Dr. Cade, a professor at the University 
of Florida Medical Center, in Gaines- 
ville, was wearing a new kind of football 
helmet that he designed. Between the 
helmet's plastic outer shell and its foam 
sponge lining there are eight small plas- 
tic bags. The bags contain oil, and they 
are connected by tiny passageways. 

A blow at one point on the helmet 
squeezes the bag underneath that point, 
making oil flow from that bag into the 
surrounding bags. The flowing oil ab- 
sorbs part of the force of the blow. Dr. 
Cade's tests show that the effect of the 
blow can be reduced by half — a com- 
forting thought for football players. 

Venice is sinking into the Adriatic 
Sea at the rate of a foot each century. 
This ancient Italian city is built on 120 
mud islands nestled in a sheltered la- 
goon. The sea water between the islands 
forms a network of 177 canals. Lined 
with magnificent buildings, the canals 
serve as streets. 

Scientists and engineers are trying to 
find out why the islands of Venice are 
sinking and what can be done about it. 
Gates could be built across the canals to 
keep the water level in the canals below 
sea level. But the gates would block the 
rise and fall of the tides, which now clean 
the canals twice a day and make sewers 
unnecessary. Also, the fish that live in the 
canals might not be able to survive in 
water that couldn't circulate between the 
sea and the canals. 



This summer's mosquito bites 

were no accident. Each mosquito had 



the same method of attack, according to 
Dr. R. H. Wright of the British Colum- 
bia Research Council in Canada. 

Dr. Wright and his fellow scientists 
have found that the carbon dioxide in the 
air a person exhales excites a mosquito. 
The mosquito then flies toward the per- 
son, moving in a zig-zag pattern through 
the stream of air coming from the per- 
son (see diagram), until it is close 
enough to see the "target." 



■M*. 







— "Vl'V 



If a person is protected by a mosquito 
repellent, however, the odor of the re- 
pellent may cause the mosquito to veer 
away from the stream. 

"Dry" water may quench your 
thirst sometime in the future. Scientists 
have recently created "powdered" wa- 
ter, made by surrounding tiny droplets 
of water with a water repellent material. 
This coating around each droplet pre- 
vents it from combining with others to 
form a pool of liquid. The result is a dry, 
white powder that is easy to store yet can 
become "wet" water again by squeezing, 
heating, or adding another substance 
that releases the water from the powder. 

There are many possible uses for "dry" 
water. For example, a "dry" water sup- 
ply could be set aside for emergency 
use. "Powdered" water could also be 
used for drinking and cooking in places 
where pure water is scarce. Perhaps it 
could be used by astronauts in space. 




This is New York City, smothered in smog. Though smog contains many dangerous 
gases, it is mainly smoke that we see. Smoke is made up of tiny bits of carbon, ash, 
oil, and other particles. The biggest particles fall to the ground as grime and soot; the 
rest hang suspended in the air until wind or rain remove them. A possible new way 
of reducing one kind of smoke pollution is described on this page. 

NATURE AND SCIENCE 



USING THIS ISSUE... 

(continued from page 2T) 

of known age may be available to 
match ring patterns with those of a 
log from an ancient hut. Or outside 
layers may have been stripped from 
the log before use. 

Objects found together may have 
been deposited at different times, by 
men, other animals, wind, or rivers. 
Or the soil may have been disturbed 
by farmers or road builders. 

If plant or animal remains are more 
than 70,000 years old, too little C-14 
is left in them to be measured. 

• Why can't living plants or ani- 
mals be dated by C-14? As C-14 in a 
living organism changes to N-14, it is 
replaced by C-14 from the atmosphere. 
Not until the organism dies does the 
C-14 in it begin to decrease. 

• Why can't sedimentary rock be 
dated by the uranium-lead method? It 
is made up of particles eroded from 
other rocks formed long before. If one 
of these particles could be dated in 
this way, the age would be that of the 
"parent" rock, not the sedimentary 
"step-parent" rock. 

• Are there other dating methods? 
Yes. There are other radioactive ele- 
ments besides uranium that change 
into lead or some other element. Each 
has a different half-life, and can be 
used to date rocks millions or billions 
of years old. 

Archeologists use a method called 
typology to determine the relative ages 
of objects such as clay pots or ivory 
harpoon tips by their shapes. They 
assume, for example, that pots of sim- 



ple shapes were made before men 
learned to make pots of fancier shapes. 

References 

For you or your more advanced 
pupils: Calendars to the Past, by Gor- 
don C. Baldwin, W. W. Norton & 
Company, Inc., New York, 1967, 
$3.48; Science and the Secret of Man's 
Past, by Franklin Folsom, Harvey 
House, Inc., Irvington-on-the-Hudson, 
N.Y., 1966, $5. 

Putting a Frog "to Sleep" 

Although results may vary with the 
species of frog and other factors, the 
author found that frogs usually dive 
to the bottom and try to burrow there 
when the water temperature reaches 
about 44° to 46°F. If you have mud in 
the bottom of the jar the frog will 
probably bury its head. The mud will 
be stirred up, however, so gravel is 
suggested as the bottom material if 
you want to observe the frog's attempt 
to dig under. 

By the time the temperature drops 
to 41°F or lower, the frog will prob- 
ably appear dead, with its body re- 
laxed and no visible throat pulse. 

Activity 

• Your pupils might test the effect 
of cold temperatures on adult insects 
such as grasshoppers, crickets, and 
ladybugs. The insect can be put in a 
container and refrigerated. Can all in- 
sects be revived after being chilled 
for some time? Some insects, such as 
ladybugs, hibernate in winter, while 
others die, leaving eggs or other im- 
mature forms to survive the winter. 



EARTH'S ORBIT 



SUMM 




NTER 



IS THE "GREAT ICE AGE" OVER? Showing your pupils how the earth's tilt and its posi- 
tion in orbit combine to produce the seasons (see diagram) may help them understand 
how the gradual changes in the tilt of the earth's axis (see page 14) and in its path 
around the sun might combine to make summers cooler for thousands of years at a time, 
favoring growth of ice sheets. When the northern hemisphere is tilted toward the sun, 
heat reaches more of the hemisphere, more directly (summer). 



Brain-Boosters 

Mystery Photo.The three long forms 
are racing "shells" that are used in 
rowing races. The canvas wrappings 
protect their smooth finish. The boats' 
oars can be seen on a rack beneath 
the boats. Can your pupils think of 
other unusual things they have seen 
carried on trucks? 

What will happen if? With a small 
test tube that just fits inside a larger 
one, you can demonstrate that when 
the smaller tube is released, atmos- 
pheric pressure forces it up into the 
larger tube as water drains out be- 
tween the two tubes. If the larger tube 
is more than half-filled with water, 
however, the smaller tube will merely 
fall out. (Hold it over a pan of water 
to cushion the fall.) 

Can you do it? No one can stand 
that way, because it leaves his center 
of mass unsupported against the down- 
ward pull of gravity (see "Where's 
Your Balancing Point?", N&S, Nov. 
13, 1967, page 13). 

Fun with numbers and shapes. The 
diagram below shows one way to make 
a square by moving only six dots. Can 
your pupils find other ways to solve 
the problem, or make up similar dot- 
arrangement problems? 



I • • • • •.— x , , 

■ » \ x . : ; 

^ n> . . . . i ! ■' 



For science experts only. As water 
freezes into ice, its volume increases 
by about 10 per cent. Since the middle 
part of an ice cube is the last to form, 
the extra volume of ice is pushed up at 
the center. 

No "bump" forms at the center of a 
frozen-over lake because a lake is not 
frozen solid. 

Just for fun. The heat from one's 
hands warms up the cold air in the 
bottle, making it expand. The expand- 
ing air forces its way past the dime 
blocking the opening of the bottle, 
making the dime move up and down 
for a short while. 



September 16, 1968 



3T 



N & S AND YOUR PUPILS 

(continued from page 1 T) 

these changes and how changes in one 
part of nature bring changes in other 
parts. 

They know that science is the pro- 
cess of investigating nature and finding 
out how it works. They have learned 
how scientists of different disciplines 
study parts of nature from different 
points of view. And they have found 
that they, themselves, can investigate 
nature and its forces in an amazing 
variety of ways. 

All these things, and more, your 
pupils have gained by reading articles 
in Nature and Science that catch and 



hold their attention, are easy to read, 
and present the concepts of nature 
and science in clear, accurate, and 
lively text and illustrations. 

Nature and Science takes your pu- 
pils on Science Adventures with sci- 
entists of the present and past; reveals 
Science Mysteries that your pupils 
may someday help to solve; shows 
them how to investigate many differ- 
ent parts of nature and poses questions 
that they can investigate for an hour, 
a day, or even a lifetime. 

Nature and Science encourages your 
pupils to find out more about their 
world and to relate what they learn to 
their own lives. 

It stimulates their imaginations and 



challenges them to think beyond the 
printed page; to identify "Mystery 
Photos" and solve scientific puzzles 
that provide a lot of instructive fun. It 
keeps them informed of current dis- 
coveries about nature. It summarizes 
basic scientific concepts and natural 
relationships for them in Wall Charts 
and other illustrations that are easy to 
follow and a delight to see. 

Nature and Science shows your pu- 
pils that science is not just for "scien- 
tists," but for everyone who seeks to 
understand himself and his environ- 
ment. It helps them see that they must 
learn to live with nature, rather than 
try to "master" it or even to just ignore 
it, if men are to survive at all ■ 



PREVIEWS OF SOME ARTICLES IN PREPARATION FOR COMING ISSUES 



LIVING WITH THE ABORIGINES A young anthropolo- 
gist and his wife find out how these primitive people can 
survive in the dry, barren, Western Australian desert. 

THE SEARCH FOR BETTER TREES Foresters are trying 
to develop "dream" trees through the use of genetics. 




THE DASHING DINOSAURS? Dinosaurs have long been 
pictured as slow, sluggish reptiles. A controversial study 
suggests that many dinosaurs may have galloped about. 

TELESCOPES IN THE SKY An astronomer who helped 
lift two telescopes above the earth's atmosphere by balloon 
tells how their failures may help make satellite-borne tele- 
scopes more successful. 

HOW AND WHY DO WE DREAM? Clues from eye- 
movements and brain waves of sleeping persons may be 
bringing scientists nearer a solution to this age-old mystery. 

RX FOR RHINOS A zoo doctor reveals how he copes with 
such problems as sick snakes and finding the right food 
for young gorillas. 

FROM THE LIGHT OF THE STARS Roy A. Gallant, 
award-winning writer of science books for children, tells 
how scientists find out what the stars are made of. 

HOW DO PIGEONS FIND THEIR WAY? Observing 
homing pigeons from airplanes, biologists have learned 
something about the mysteries of bird navigation. 



THE PHYSICS OF FASTENERS A Wall Chart shows 
how we use natural forces to hold things together. 

LIFE ON A PACIFIC ISLE Naturalist Alan Anderson tells 
how he investigated the surprisingly complex community 
of plants and animals on a tiny ocean island. 

THE EARTH IS A GIANT MAGNET What makes it so is 
a mystery that scientists are trying to unravel. 

SCIENCE WORKSHOPS: Raising spiders and studying 
their behavior. . .Exploring density in a liquid laboratory 
...What makes watery sap rise up a towering tree — or a 
celery stalk?. . .Adventures with a barometer. . .How does 
yeast "work" in foods and in cooking?. . .Making sense of 
measurements with peanuts, pennies, and probability. . . Be 
a bacteria hunter. . . 




THE EARTH'S UNSTABLE CRUST A special issue ex- 
amines the forces that seem to cause earthquakes, build 
mountains, and push the continents away from each other. 

LIFE IN A CITY A timely look at the ecology and tech- 
nology of cities — how cities are planned (or unplanned), 
why some kinds of plants and animals thrive in cities while 
others die out, how cities affect their own weather, and 
how to study the lives of common city animals. 

SURVIVAL IN THE ARCTIC This special issue explores 
how and why men, polar bears, and many other forms of 
life exist in the arctic, and tells what scientists are trying 
to learn about life there. 



4T 



NATURE AND 5( li:NCE 



nature and science 

TEACHER'S EDITION 

VOL. 6 NO. 2 / SEPTEMBER 30, 1968 / SECTION 1 OF TWO SECTIONS 

COPYRIGHT © 1968 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 



N & S REVIEWS ► 

Recent Life Science Books 
for Your Pupils 

by Barbara Neill 



nature 
and science 



The Struggle for Life in the Animal 
World, by Shelly Grossman (Grosset and 
Dunlap, 128 pp., $4.95). Outstanding 
photographs taken by the author during 
four years of travel portray the natural 
: world of North America and the lives of 
j its animal inhabitants. The text is accu- 
i rate, easy to read, and suitable for a sixth 
i grader. The ecologies of a number of 
different communities are explored. The 
land requirements of animals, their num- 
bers, competition, relationships with 
j each other and with man are explained 
J in a way that should awaken the reader 
i to a better appreciation of the interde- 
pendency of life everywhere. 

The Mighty Human Cell, by Patricia 
Kelly (John Day Co., 128 pp., $3.86 in 
library binding). In order to simplify a 
complex subject for children, a writer 
must know it thoroughly. In this case the 
author is trained in cytology and is work- 
ing in the field. The result is a consist- 
ently readable book which explains so 
well the functions of cells that children 
will gain a clear understanding of the 
workings of the whole human body. The 
necessary technical words are accom- 
panied by an explanation and pronuncia- 
tion guide, and there is a glossary. A 
fascinating book for grades five and up. 

Strange Fishes of the Sea, by Olive L. 
Earle (Wm. Morrow, 64 pp., $2.95). In 
the ocean depths there is a little fish 
called the great gulper that has an ex- 
pandable stomach and a long spiny tail 

Barbara Neill is a Senior Instructor in the 
Education Department of The American 
Museum of Natural History in New York. 



with a light organ at the tip; in the Sar- 
gasso Sea there is a fish whose ragged 
fins and many appendages match per- 
fectly the surrounding plants. Sawfishes, 
sea horses, stonefishes, and swellfishes 
are some of the other odd fishes in this 
book for 8- to 12-year-olds. The book 
will entertain children, and may arouse 
their curiosity to learn more. Illustrated 
with the author's drawings. 

Wonders of Fossils, by William H. 
Matthews III ( Dodd, Mead & Co., 64 pp., 
$3.25). Fossils fascinate many children 
and this good introduction to the subject 
should be just right for those from the 
fifth grade up. It tells of the many ways 
fossils are formed and of their signifi- 
cance to geologists and other scientists. 
The various kinds of fossils are dis- 
cussed, and they are grouped scientifi- 
cally with their classification explained. 
The last two chapters are devoted to 
finding fossils and making a worthwhile 
collection of them. There is an excellent 
bibliography. 




Science Explorer: Roy Chapman An- 
drews, by Jules Archer (Julian Messner, 
191 pp., $3.50). Roy Chapman Andrews 
was a scientist with an explorer's energy 
and temperament, and his life was a 
(Continued on page 8T) 







M <• 



IN THIS ISSUE 

(For classroom use of articles pre- 
ceded by •. see pages 2T and 7T.) 

The Case of the Deep Ocean Trail 

A mysterious trail found 10,000 feet 
below the Pacific Ocean has set scien- 
tists off on a search for the unknown 
animal that made it. 

• Brain-Boosters 

• Living with the Aborigines 

In this Science Adventure, a 
young anthropologist's wife tells 
how she and her husband began to 
investigate the lives of these native 
Australian people. 

• Visit to a Plant Factory 

This Wall Chart gives your pupils 
an inside view of how a plant func- 
tions. 

• How Dense Are You? 

Your pupils will have fun compar- 
ing the densities of different mate- 
rials and objects (even the human 
body) in this investigation. 

The Ways of a Spider 

By observing and collecting spiders 
and their webs, your pupils can 
learn about the lives of these tiny 
animals. 

How Leaves Change Color 

A botanist explains what causes the 
colorful changes in leaves that your 
pupils will see this fall. 

IN THE NEXT ISSUE 

Part 2 of "Living with the Aborig- 
ines": gathering food in the desert 
. . . How Aborigines used boomer- 
angs and why some boomerangs 
return . . . Science Workshop and 
Wall Chart on the autumn disper- 
sal of seeds ... Exploring drops. 



USING THIS 

ISSUE OF 

NATURE AND SCIENCE 

IN YOUR 

CLASSROOM 



Living with the Aborigines 

Getting to know people who are in 
some way or other different from one- 
self is one of the most satisfying expe- 
riences a person can have. It is also 
useful, because people who live in dif- 
ferent ways can usually learn something 
from each other. And it is probably 
beneficial to our species, because peo- 
ple who understand each other tend to 
respect each other, even if they don't 
agree about everything. This article 
will give your pupils insight into both 
the problems and benefits of getting to 
know someone "different" from one- 
self. 

Suggestions for Classroom Use 

• Have some of your pupils who 
have moved from one place to another 
try to describe their feelings and expe- 
riences in making new friends. Can 
they think of some things that people 
in the "new" place did differently from 
the people they lived among before? 
How did they go about getting ac- 
quainted? Did they invite people they 
had just met into their homes? Or 
share some candy with them? Or show 



NATURE AND SCIENCE is published for The American 
Museum of Natural History by The Natural History 
Press, a division of Doubleday & Company, Inc., fort- 
nightly September, October, December through March; 
monthly November, April, May, July (special issue). 
Second Class postage paid at Garden City, N.Y. and at 
additional office. Copyright © 1968 The American 
Museum of Natural History. All Rights Reserved. Printed 
in U.S.A. Editorial Office: The American Museum of 
Natural History, Central Park West at 79th Street, 
New York, N.Y. 10024. 

SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester 
per pupil, $1.95 per school year (16 issues) in quanti- 
ties of 10 or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's 
edition $5.50 per school year. Single subscription per 
calendar year (17 issues) $3.75, two years $6. Single 
copy 30 cents. In CANADA $1.25 per semester per 
pupil, $2.15 per school year in quantities of 10 or more 
subscriptions to the same address. Teacher's Edition 
$6.30 per school year. Single subscriptions per cal- 
endar year $4.25, two years $7. ADDRESS SUBSCRIP- 
TION correspondence to: NATURE AND SCIENCE, The 
Natural History Press, Garden City, N.Y. 11530. Send 
notice of undelivered copies on Form 3579 to. NATURE 
AND SCIENCE, The Natural History Press, Garden City. 
N.Y. 11530. 



them a new game or skill? 

Did they learn about something 
from their new friends— games, books, 
TV shows, foods, and so on? Did their 
feelings about the people in the new 
place change as they got to know them? 
Have your pupils compare their reac- 
tions with those of Mrs. Gould as she 
got to know the Aborigines. 

• Have your pupils compare vaca- 
tion trips on which they stayed with the 
same people a week or two with trips 
on which they kept traveling from 
place to place. In which case did they 
get to know the people in a new place 
best? Even when they spent two weeks, 
say, with the same people, did they 
find out much about how those people 
live every day? 

• Ask your pupils whether they act 
the same way and do the same things 
when they have guests in their home 
as they do at other times. Or do they 
act differently to "please" their guests 
—or perhaps to "impress" them? Can 
they relate these experiences to the 
Goulds' living for months with the 
Aborigines? (An anthropologist can 
find out more about a group of peo- 
ple's everyday habits when he has been 
with them long enough for them to 
think of him as a group member.) 

Topics for Class Discussion 

• Why are these people called "Ab- 
origines"? Aborigine is a general word 
meaning a people— or other animal, or 
plant— that has lived in a certain area 
"since the beginning." No one knows 
exactly when the Australian Abori- 
gines reached that continent, but it was 
at least 20,000 years ago, long before 
Europeans settled there in 1788. 

• Are the American Indians abori- 
gines? Yes. Their ancestors came to 
North America from Asia at least 
15,000 years ago. 

• Why was Dr. Gould so inter- 
ested in finding out how the Aborigines 
made and used stone tools? For over a 
million years before metals were used, 
men depended on tools of stone (which 
were used to make tools of wood or 
bone). Today when archeologists un- 
earth stone handaxes, knives, scrapers, 
and so on, they can only guess about 
how the tools were made and used. 



Knowing that a few of the Aborigines 
still had this skill, Dr. Gould was 
anxious to see it demonstrated first 
hand, before the secret died out with 
its owners. 

Visit to a Plant Factory 

All life on earth depends on green 
plants and their ability to change en- 
ergy from the sun into food energy 
through the process of photosynthesis. 
People tend to think that milk, meat, 
bread, fish, and other foods come from 
stores; but it all comes from green 
plants, either directly or indirectly. 

Comparing a plant with a factory is 
a useful device for teaching about the 
food-making process in plants. Point 
out to your class, however, that a plant 
is like a factory only in a limited sense. 
It is a living organism, the product of 
millions of years of evolution, and can 
build, repair, and reproduce itself. 

Activities 

• You can demonstrate the flow of 
liquids up the stem of a plant by set- 
ting a fresh stalk of celery (with leaves 
on) in a glass of water colored with 
food coloring. Make a fresh cut at the 
bottom of the stalk and leave it over- 
night. The color will move up the stalk 
to the leaves. If you look at sections 
cut from the stalk you can see the col- 
ored xylem tubes. (Do your pupils 
suppose the water would rise to the 
tip of the stalk if you put the leafy end 
in the colored water?) 

• To see root hairs, soak some rad- 
ish seeds overnight, then keep them on 
a wet blotter in a dark place for two 
or three days. Primary roots will grow 
directly from the seeds, and other roots 
will grow from them. With a magnify- 
ing glass you will be able to see the 
fuzzy root hairs at the tips of the larger 
roots. 

How Dense Are You? 

After your pupils have feigned insult 
from this title and run out of wise- 
cracks about "intelligence tests," they 
may be surprised to learn that density 
is a scientific concept describing the 
closeness with which matter is packed 
(Continued on page IT) 



2T 



\ Ml HI l\/) S( // \( / 



for classroom 
bulletin boards, walls, 
exhibitions, displays . . . 
a complete set of 10 NEW 

nature and science 




For chalkboard, bulletin board, wall— for sci- 
ence exhibitions and displays— here are last- 
ing sources of information that are always 
ready to catch (and educate) the wandering 
eye of any student: 

all fully illustrated in vivid color! 
each chart an abundant 22 by 34 inches', 
printed on durable, quality stock! 
delivered in mailing tube for protection 
and storage! 




Reproduced from the pages of NATURE 
AND SCIENCE— and enlarged 300% in 
area— these wall charts cover a range of 
topics every science class should know 
about: the solar system, botany, energy, 
geology, conservation, disease, ecology, 
reproduction, evolution, communication. 
Use these dramatic visual aids to clarify 
concepts and relationships as you 
discuss them with your pupils. 



These impressive charts are especially pre- 
pared by the editors of NATURE AND SCIENCE 
working under the supervision of scientists at 
the world-famed American Museum of Natural 
History. All are tested teaching aids— designed 
to stimulate as many questions as they answer! 
Each is 22 by 34 inches— a full 748 square 
inches of information! All are printed on dura- 
ble, opaque vellum for easy mounting and per- 
manence. Non-glossy finish eliminates glare, 
helps assure visibility from any angle. And all 
are illustrated in dramatic color. 



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Make Your Classroom Walls 
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VOL. 6 NO. 2 / SEPTEMBER 30. 1968 



nd science 



What animal made 
those strange tracks 
on the ocean floor? 

see page 2 

THE CASE OF THE 
DEEP OCEAN TRAIL 




Picking his teeth? 

or 

Sharpening a stone? 

see page 4 

Living with 
the Aborigines 






" 



s 




V 









m ooiliiol ivi i o i crv I 



VOL. 6 NO. 2 / SEPTEMBER 30, 1968 



CONTENTS 

2 The Case of the Deep Ocean Trail 




4 Brain-Boosters, by David Webster 

5 Living with the Aborigines (Part 1), 

by Elizabeth B. Gould 

8 Visit to a Plant Factory 
1 How Dense Are You?, by Robert Gardner 

12 What's New?, by Roger George 

1 3 The Ways of a Spider, 

by Margaret J. Anderson 

1 5 How Leaves Change Color, 

by Richard M. Klein 






PICTURE CREDITS: Cover, pp. 5-7, by Richard A. Gould; p. 3. photo 1 from 
U.S.S.R. Academy of Sciences. 2 from New York State Museum, bottom by 
Leonard L. Rue 111; pp. 4, 5, 8-15, drawings by Graphic Arts Department. The 
American Museum of Natural History; p. 4. photo by Douglas Seager; p. 10, 
photos by Kranklyn K. Lauden; p. 12, photo from The New York Times: p. 14, 
photo by John H. Gerard from National Audubon Society. 






" 



PUBLISHED FOR 

THE AMERICAN MUSEUM OF NATURAL HISTORY 

BY THE NATURAL HISTORY PRESS 

A DIVISION OF DOUBLEDAY & COMPANY, INC. 

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publisher James K. Page, Jr.; circulation director J. D. Broderick 
promotion director Elizabeth Connor 
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PAUL F. BRANDWEIN, CHAIRMAN, Dir. of Research, Center for Study of 
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'ffieCase 
gfthe 

Deep 

Ocean 

Trail 



■ About 10 years ago an underwater camera on a Russian 
research ship took a photograph (Photo I) of the sea 
floor 10,000 feet under the Pacific Ocean. The curving 
"tire tread" marks appear to be the trail left by a deep-water 
animal. But what animal is it? 

Two Russian experts admitted they didn't know. But 
they thought the trail looked like other unidentified trails 
photographed by British explorers in the Atlantic Ocean at 
almost twice the depth of the Russian photo. 

Today scientists are still searching for the animals which 
leave these strange trails on the sea floor. In a recent issue 
of Natural History magazine, Dr. O. C. Farquhar, a geol- 
ogist at the University of Massachusetts, in Amherst, wrote 
about some strange clues that scientists have. 

These clues were found over a hundred years ago in the 
rocks of eastern North America. There, preserved in the 
rocks as fossils, are trails left by other mystery creatures 
half a billion years ago (see Photo 2). Dr. Farquhar 
compared these fossil trails with the new trail from the 
Pacific. He found that the shapes of the trails arc similar. 
That means that the animals which made the old and new 






NATURE AM) SCIENCE 












Photo 1 shows the trail left by an unknown animal, 
10,000 feet deep in the Pacific Ocean. The trail is about 
4 inches wide. The fossil tracks in Photo 2, found in 
rocks of eastern North America, are between 5 and 6y 2 
inches wide and were made half a billion years ago. At 
the left side of Photo 2 you can see a mark made by the 
animal before it started to move. 



trails probably had similar bodies, including a tail which 
dragged along behind. 

The trails are also about the same size. The new trail 
in the Pacific is about 4 inches wide, and the fossil trails 
from North American rocks are from 5 to 6V2 inches wide. 

The new trail in the Pacific was made in deep water in 
a soft ooze or sand. The fossil trails were found on dry 
land. But half a billion years; ago, when these trails were 
made, a shallow sea covered much of the eastern part of 
North America. Later the sandy bottom of the sea hard- 
ened into sandstone, preserving the trails as fossils. So the 
old and new trails were made in habitats, or living places, 
that were alike in some ways. 

Dr. Farquhar thinks these similarities between the old 
and new trails mean that the animals that made the fossil 
trails may have been the ancestors of the animal that left 
the tracks in the Pacific. 

What Is at the End of the Trail? 

One difference between the trails shown in the two 
photos is the egg-shaped imprint at one end of the fossil 
trail. The imprint probably is the mark left by the animal 
before it started to move. The photograph of the trail ffqm 
the Pacific shows nothing like this egg-shaped imprint. But 
this may be because the photo does pot show the beginning 
or end of the trail. 

Donald W. Fisher, New York's State Paleontologist, 
thinks that the fossil trails may have been made by crea- 
tures that were related to the horseshoe crab (see photo 
below), which leaves a similar trail. If this is so, then the 
trail photographed in the Pacific may also be of some ani- 
mal related to the horseshoe crab. 

The identity of the mystery animal won't be known until 
the creature and its trail are seen at the same time, in the 
same place. As scientists explore the ocean, their under- 
water cameras may someday photograph the mysterious 
trailmaker itself ■ 



■ - 




.j* -> 



Two horseshoe crabs 
made these tracks in 
wet sand. Both the deep 
ocean trail and the fos- 
sil trail may have been 
made by some animal 
related to the horseshoe 
crab. 



September 30, J 968 



When the person who took this picture of the setting 
first saw the photo, he was surprised to see the eight 
crescent "moons" around the sun. Can you explain what 
might have made these bright marks? 




prepared by DAVID WEBSTER 




WHAT WILL HAPPEN IF? 

Make a pinhole in a large balloon, and place 
the "mouth" of the balloon over the bathtub 
faucet. Turn on the water slowly and support 
the balloon as it fills with water. As 
the balloon becomes larger, what 
happens to the stream of water that 
squirts out of the pinhole? 



CAN YOU DO IT? 

Mix together a little salt and pepper. Can you separate the 
pepper from the salt? 

Submitted by Gary French, La Mesa, California 

FUN WITH NUMBERS AND SHAPES 

Suppose that you and I had some pennies. If I gave you 
one of my pennies, we would each have the same number. 
If you gave me one of your pennies, however, I would have 
twice as many pennies as you. How many pennies do I have? 

FOR SCIENCE EXPERTS ONLY 

Can you figure out the secret message? 

IFY OULOO KCA RE FUL LYYOUS HOUL 
DBEAB LE TOF IGUR EOUTT HISM ESS AGE 

JUST FOR FUN 

Put an uncooked egg on a plate and spin it around as fast 
as you can. While it is still spinning, stop it for an instant 
with your finger. If the egg is let go immediately, it will 
start to spin again. This is because 
the insides of the egg keep spinning 
for a few seconds after the shell is 
stopped. 

4 




■ANSWERS TO BRAIN-BOOSTERS- 
IN THE LAST ISSUE 



Mystery Photo: The truck is carrying three large racing 
shells that are used in rowing races. The boats are 
wrapped in canvas to protect their smooth finish. The 
oars are on the rack beneath the boats. 

What will happen if? When the smaller test tube is let go, 
it is drawn slowly up into the larger test tube as the water 
drains out between the two tubes. Would the same thing 
happen if the larger test tube were three-quarters filled 
with water? 

Can you do it? It is impossible to hold your left leg in the 
air while standing with your right side touching a wall. 

For science experts only: An ice cube forms first around 
the outside; the middle becomes ice last. Since water ex- 
pands as it freezes, some ice is pushed up in the center of 
the cube. Why doesn't a frozen lake have a large bump 
in the middle, too? 

Fun with numbers and shapes: Here is how to form a 
square by moving only six dots. 




o o 



NATURE AND SCIENCE 



A SCIENCE ADVENTURE 





ifhtk 



o o 





Part 1 

A young scientist's wife 
tells how she and her husband 
made friends with some of 
these primitive people to find 
out how they and their 
ancestors managed to survive 
in the hot, dry Western 
Australian desert. 

by Elizabeth B. Gould 




Fresh from the desert, where they lived 
by hunting and gathering food, this family 
of Aborigines camped near a church mission. 
They were given cast-off clothing, waste 
materials for a shade shelter, 
and free government food. 



■ When my husband and I went to Australia two years 
ago, we faced more than the usual problems people have 
when they go someplace new and try to make friends. The 
people we went to live with speak a different language and 
live by hunting and gathering food in a hot, dry desert; 
they have never seen an ocean or snow, or sat in a chair 
or slept in a bed. They are a group of people called 
Aborigines (ab-orij-in-eez), some of whom still live in 
the Gibson Desert of Western Australia (see map). 

You might wonder why anyone would want to spend 
15 months with people whose ways of living are so dif- 
ferent from their own. My husband, Dr. Richard Gould, is 
an anthropologist at The American Museum of Natural 
History, in New York City. (An anthropologist is a scien- 
tist who studies how humans and their ways of living 
have changed down through the ages.) A few of the Abor- 
igines still live in the way their ancestors did for centuries, 
and we wanted to find the answers to some questions that 
no one had asked these people, as far as we knew. 

There wasn't much time left. Most of the native Aus- 
tralians had been moved to large government settlements 
where they could be taken care of and educated. Soon they 
would no longer need to know many of the things that 
made them different from any other people on earth. 

Before going to Australia, we tried to prepare ourselves 

September 30, 1968 



by reading books and talking with other anthropologists 
who had studied the Aborigines' way of life. We knew it 
would not be easy to live in the desert; we would have to 
carry our own food and water with us, because we wouldn't 
know how to find it ourselves. 

In 1966 we flew to Perth, Australia, and began to gather 
our supplies together. We got a Land-Rover, a truck that 
can go through mud, over sand, and up steep hills. It had 
extra tanks that held 37 gallons of gasoline and 30 gallons 
of water. We bought a tent, sleeping bags and air mat- 
tresses, mosquito netting, lanterns, and all sorts of camp- 
ing supplies. 

Probably the most important piece of equipment was a 
two-way radio, which we could use to keep in contact 
with civilization or to call for help if we were in danger. 
To make a permanent record of our experiences, we took 
several cameras and a tape recorder. We bought hundreds 
of cans of food: meat, vegetables, fruit, milk— everything 
that comes in a can. It was not a very appetizing diet, but 
it was easy to carry and prepare. 

Dust, Stars, and Kangaroos 

From Perth, we drove toward a little town called Laver- 
ton, about 600 miles away (see map). The last 150 miles 

(Continued on the next page) 



Living with the Aborigines (continued) 

were not paved, and we stirred up great clouds of dust as 
we drove. It was March, toward the end of the Australian 
summer, and the days were hot and uncomfortable. But 
the evenings were cool and pleasant and it was nice to roll 
out our sleeping bags and sleep under the cloudless sky 
that seemed crowded with unfamiliar constellations. 

Toward evening kangaroos started to appear, hopping 
along and looking so ridiculous that we had to watch until 
they were out of sight. What was still new to us was a 
bother to Australians: kangaroos are a hazard to night 
driving; they often collide with cars. 

At Laverton, we found a place to pitch our tent and 
spent the first day putting our camp in order. I was a 
little afraid of meeting the Aborigines— I didn't know if 
they would like me, or even talk to me. But they were our 
reason for being there, so we went to their camp. 

There were about 350 Aboriginal people crowded to- 
gether on a Government Reserve that was no bigger than 
a few city blocks. They lived in little wiltja, or shade 
shelters. These were once made of branches arranged in a 
semicircle, but were now made with old blankets and 
scraps of tin or canvas barely supported by crowbars and 
pieces of wood. The people sat around these shelters with 
their little fires in front of them, even in the intense heat. 

The countryside surrounding the Reserve had been 
picked clean of firewood, and the whole place was very 
bare and dusty. When the wind blew, dozens of pieces of 
litter and garbage were picked up and whirled around the 
camp. Very thin dingos, or Australian dogs, sniffed and 
scavenged around the camp, and noisy crows swarmed 
overhead. 

It was about the most depressing place I could have 
imagined. Where were the skilled hunters, the people who 
were clever enough to make their living in a parched 
desert? All I saw were people living in squalor and grow- 
ing fat on the food given them by the government. 

Meeting the Aborigines 

I remembered, though, that these people hadn't been 
confined together like this all their lives. They could still 
teach us a great deal; they still must remember how to 
gather food and find water. So I went to meet them. 

My husband had begun by showing an interest in the 
tools the men always carried with them— their spears and 
spearthrowers. He had asked about the designs on them, 
what kind of wood they were made of, and where those 
trees grew. Since my husband had a Land-Rover, he of- 
fered to take the men to find spearwood. But what could I 
find to talk about? 

I saw a little group of young women sitting on a ragged 
blanket between two shelters. Armed with paper and 
crayons and some candy for the children, I went over to 



them. They politely moved over to give me some room 
on the blanket, and I sat down. They noticed me and they 
ignored me at the same time, it seemed. I felt awkward 
and foolish. 

There were a few men sitting not far off, and one of 
them began to sing a fast, short song. The women roared 
with laughter! I was the only one who didn't get the joke, 
and I couldn't have felt lonelier. But I stayed and offered 
my paper and crayons to one of the women, indicating that 
I would like her to draw me a map of her "country." 

The Aborigines have very close ties to their land. They 
know every waterhole and every natural feature of the 
landscape in the places where they usually hunt and gather 
food. They have memorized the waterholes in order, and 
they can draw "maps" which are merely circles connected 
by straight lines. Each circle, or waterhole, has a name, 
which I wrote down as they told me. Some of these women 
had been to a mission school and spoke a little English. 
We had learned something about their language from a 




Innl 



OOIS 




Dr. Richard Gould, shown 
leaning against a large ter- 
mite hill in the desert, wanted 
to find out how the Aborigines 
made and used stone tools 
before the Europeans brought 
metal tools to Australia. One 
of the few Aborigines left who 
still know how to do this 
agreed to show him. He found 
a water-worn pebble and 
struck it with other stones and pointed sticks, chipping off 
flakes until the stone was fairly flat and thin-edged. Then he 
cemented it to the handle of a spear-thrower (see photos at 
right) with a lump of plant resin. To sharpen the edge, he 
chewed fine flakes off the stone with his teeth (see cover 
photo). It takes strong jaws and flat-topped teeth to do this, 
and the Aborigines get both through years of using their 
teeth as tools and eating gritty foods. 



An Aborigine strips bark from a spear stick with his teeth. 



NATURE AND SCIENCE 



book, so I could understand a little of what was being said. 

I spent almost two hours trying to make friends, and I 
was uncomfortable most of that time. I felt like a curiosity 
in their world, and hearing so many new words and trying 
to remember what they meant was very tiring. 

When I got up to go, I could scarcely stand up, much 
less walk! I had been sitting with my feet almost tucked 
under me, imitating their position, and both feet were 
asleep and prickly. Learning to live with the Aborigines, I 
thought, would take physical as well as mental efforts! 

"America Must Be a Strange Place" 

The first weeks were the hardest, with many surprises, 
disappointments, and discoveries. As we got to know the 
Aborigines better, we learned that they were very cour- 
teous and pleasant people, and they were quite willing to 
answer our questions. In return, they asked where we 
came from and why we wanted to know about them. They 
thought America must be a very strange place with no 



kangaroos or large emu birds or mulga trees. 

But these Aborigines were not very happy people, be- 
cause their way of life was changing so rapidly. They had 
been moved hundreds of miles from the land they loved, 
and they longed to go back to their homes. At the same 
time the Aborigines were learning about white people, and 
they, too, wanted to have things like cars and clothes and 
money. 

We knew we would have to go farther into the desert to 
find Aborigines who were still hunting and gathering food 
on the land that meant so much to them. So after three 
months at Laverton, we packed up our camp and started 
for Warburton Ranges, a place 370 miles further up the 
dirt road. We were sorry to be leaving the Laverton people 
just as we were beginning to know them. We were sorry. 
too, that their lives had changed so much ■ 

In the next issue, Mrs. Gould tells how Aborigines living 
in the desert find enough food to survive. 




The thin, curved spear- 
thrower, shaped with stone 
tools from a piece of tree 
trunk, can also be used as a 
mixing tray or as a "clapper" 
for ceremonial dances. (This 
thrower has not yet been 
tipped with stone.) 



The stone-tipped spear-thrower also makes a well- 
balanced scraping tool for shaping and pointing a 
spear or digging stick. Its light weight and many 
uses made the spear-thrower a handy tool for peo- 
ple who travelled "light." 




Using the spear-thrower as a lever, an Aboriginal hunter can throw 
a spear about 120 feet and hit a small animal. The hunter lets go of 
the spear as he swings the thrower forward, and a hook at the end 
of the thrower pushes the spear ahead with great force. 










£ £ A V$ 



ifi, «L a) 
* £ > 

W O 






o «. "ij <j 






<A 









A * 




Which of the two 
metal blocks in this 
photograph do you 
think is heavier? 


&'*&./■ i:.-1yfij 






H 


1 1 '\V vSB! 





You might guess that the bigger one weighs more. 
After all, a big rock weighs more than a small one, 
a gallon of milk is heavier than a glassful, and a 
fishing sinker weighs more than a BB. But does a 
ping-pong ball weigh as much as a golf ball? Does a 
baseball weigh the same as a tennis ball? 




As you can see from this photograph, the little block 
is heavier than the big one. One of the blocks is 
made of lead; the other is aluminum. Can you guess 
which one is lead? 



SCIENCELEC 



How 

Dense 

Are You? 



■ A piece of lead weighs more than four times as much as 
a piece of aluminum of the same size. You might say that 
lead is much more compact— more closely packed together 
—than aluminum. Scientists say that lead is more dense 
than aluminum. 

If you divide the weight of any piece of material by its 
volume (the space that it takes up), the figure you get is 
called the weight density of that material. For example, 
two cubic feet of water weigh 124.8 pounds, so the weight 
density of water is: 
124.8 lbs. 



2 cu. ft. 



= 62.4 pounds per cubic foot. 



Here are the weight 


MATERIAL 


WEIGHT 
DENSITY 

(lbs. per 
cu. ft.) 




Water 


62.4 




densities of some mate- 


Gasoline 


41.2 


rials you have probably 


Aluminum 


168.7 


seen. Which of these 


Lead 


712 


materials is the most 


Gold 


1,205 


dense? Which is least 


Iron 


493 


dense? Which sub- 


Glass 


150-175 


stances seem to have 


Wood (balsa) 


7-8 


about the same density? 


Wood (oak) 


37-56 




Quartz 


165 




Air 


0.08 



You can find out which of two materials is more dense 
by hanging equal volumes of each material from the ends 
of a balance like the one shown below. Try it with a small 
block of wood and a clay block that you have molded to 
the same size and shape as the wooden block. Which block 
is more dense? (If you squeeze the clay block into a dif- 
ferent shape, does its density change?) 



sticky 
tape 




icil or 

dowH 



Make a balance like this 
to compare densities of 
different materials. If 
the balance beam is not 
quite level, add a small 
piece of clay to the light 
side of the beam, as 
shown in the photo of a 
balance on this page. 

NATURE AND SCIENCE 



PROJECT 



Is a stone more dense than steel washers? To find 
out, you will have to figure out a way to get equal (or 
nearly equal) volumes of stone and washers. (Hint: 
An object that sinks in water displaces a volume of 
water equal to the object's volume.) 



Is cooking oil more or less dense than water? To find 
out, use your balance to compare the weights of equal 
volumes of these liquids. (You might use a kitchen measur- 
ing cup to measure out 2 liquid ounces of each. ) Is rubbing 
alcohol more dense than water? Than cooking oil? 

Where Does the Drop Go? 

There is another way to compare the densities of liquids. 
From the results of your weighings, what do you think will 
happen if you slowly squeeze a drop of cooking oil from 
the end of a medicine dropper into the middle of a con- 
tainer of water (see diagram)? Will the drop go up, down, 
or stay in the middle? What will happen if you 
squeeze a drop of water into some cooking 
oil? Into some alcohol? 

Do you think the "drop test" for comparing 
densities is as useful as the "balance test"? 
You can find out by preparing some liquids 
that differ only a little bit in density. Line up 
four glasses about % filled with water. Add one tablespoon 
of salt to one glass of water, two tablespoons to another, 





and three to another. Stir all three liquids until the salt has 
completely dissolved. Add a drop or two of food coloring 
to the liquids. You might color one liquid red, another 
blue, a third green, and leave the one without any salt in 
it clear. 

Try to work out the order of density of the four liquids 
from 1 . Densest to 4. Least dense by the balance test. Now 
try to work out the order of densities by the drop test. You 
might put samples of each liquid into pill bottles or test 
tubes and add drops of one to the others. How many dif- 
ferent combinations are there to try? Do you think the drop 
test or the balance test is better for comparing the densities 
of liquids? 

September 30, 1968 



PROJECT 

If you have some transparent soda straws or tall 
thin pill bottles, you might like to see whether 
you can layer your colored liquids. Can you 
make two, three, and four layers of liquids? How 
many different two, three, and four-layered liq- 
uids can you prepare from your four solutions? 
If you use other liquids, how many layers can 
you make? 





You might try to find out where some other liquids 
would fit in your density order. Try alcohol, cooking oil, 
vinegar, sugar water, apple juice, milk, and so on. 

Which Gas Is Denser? 

As you can see in the table on page 10, air has a very 
low density. Do you think that all gases have the same 
density? Does carbon dioxide gas have the same density as 
air? To find out, get two balloons and tie-bands that have 
the same weight (see diagram). Then prepare some carbon 




band 




Alka-Seltzer 
and water 



dioxide gas by breaking in half three or four Alka-Seltzer 
tablets and dropping them into about an inch of water in 
a small pop bottle. Attach one of the balloons to the neck 
of the bottle to collect the gas. Close the balloon with the 
tie-band and remove it from the bottle. Then use a bicycle 
pump to put an equal volume of air into the second balloon. 
Use the balance test to find out whether one gas is denser 
than the other. 

Suppose you replace the "pump air" in the second bal- 
loon with "lung air." How will the density of "lung air" 
compare with that of carbon dioxide? With that of "pump 
air"? Can you explain your findings? ■ 

r — MORE INVESTIGATIONS — - 

• Using the drop test, can you find any difference in 
the density of hot and cold water? 

• Are all solids more dense than all liquids? How 
about wood and water? Clay and water? Wood and 
alcohol? You can probably think of many other materi- 
als to compare for density. 

• Is your bath soap more or less dense than water? 



11 



WHAT'S 
NEW 




ae 



by 

Roger Georg 



A shot that misses can still kill a 
duck. When a hunter fires a shotgun at 
a duck, many lead pellets miss their mark 
and drop into the water. As ducks probe 
for food on the water's bottom, they often 
swallow these pellets by mistake. A pellet 
stays in the duck's gizzard until it is 
gradually absorbed into the digestive 
system. There the lead can cause poison- 
ing and death. Scientists believe a single 
pellet can kill a duck in this way. 

After 10 years of seeking a solution 
to this problem, the National Research 
Council of Canada reports progress. 
Their scientists are trying to make a 
pellet of lead powder held together by 
an adhesive that will "let go" when it 
gets wet. Thus the pellet would fall apart 
in water and be less dangerous to ducks. 



A flight to four outer planets 

ought to be launched in 1978, say some 
American space scientists. At that time 
Jupiter, Saturn, Uranus, and Neptune 
will be lined up so that an unmanned 
spacecraft could pass close to each one 
(see diagram). The gravitational pull of 



989 




each planet could then boost the space- 
craft's speed enough to carry it to the 
next planet. The spacecraft would cover 
the 2.7 billion miles from the earth to 
Neptune in about 1 1 years. The planets 
won't be arranged like this again until 
the year 2157. Meanwhile, the only way 
to reach Neptune would be a direct flight 
lasting 30 years, and no existing space- 
craft has the power to do it. 

Spacecraft have flown by Mars and 
Venus, but no flight has yet reached the 
outer planets. One of the biggest obsta- 
cles in the way of such a flight would be 
its high cost. 




Holding a fishy treat in one hand and a drugstore-window toothbrush in the other, 
Pedro Ponciano brushes some stains from the teeth of a killer whale at the New York 
Aquarium in New York City. Killer whales can be dangerous, so the keeper tries not 
to get too close. "I feel we have become friends," he says, "but I am not ready to get 
into the tank with her yet." The whale has other problems besides stained teeth. The 
white area on the whale's head is a treatment for sunburn. 



Birds of a feather flock together, 

but why do they? Probably because each 
bird has gotten used to being with its 
own kind from the time it was hatched, 
according to Dr. E. A. Salzen and Dr. J. 
M. Cornell of the University of Waterloo, 
in Canada. 

The two scientists dyed some newborn 
chicks red, others green, and left some 
yellow. When chicks of one color were 
raised together for eight days and then 
put with chicks of other colors, they 
stayed with chicks of only their own 
color. But when chicks of different colors 
were raised together, none of the chicks 
seemed to prefer chicks of its own color 
to chicks of the other two colors. Chicks 
raised alone didn't develop any color 
preference, unless they were able to see 
their own reflections in drinking water. 



Cavemen liked flowers. At least, 
scientists investigating a grave deep in a 
cave in Iraq think they did. The scientists 
found the remains of a Neanderthal man 
who had apparently been buried on a bed 
of flowers. 

A French scientist, Mrs. Arlette Leroi- 
Gourhan, found pollen of at least eight 
kinds of wildflowers in soil taken from 
the grave. The flowers were related to 
wildflowers now growing on the hillsides 
around the cave. This suggests that the 
flowers were gathered outside the cave 
and brought to the burial site. 

Neanderthal men were the first pre- 
historic people to bury their dead, so 
their graves often \ ield valuable clues to 
the historv of man. 



Insects may hold the secret to bet- 
ter television reception. A TV antenna 
"picks up" waves of electromagnetic 
energy that the TV set changes into pic- 
tures and sounds. A pair of antennae 
on the head of an insect may detect 
sound waves, odors, or even light waves 
(also waves of electromagnetic energy). 

P. S. Callahan, a scientist at the Uni- 
versity of Georgia, in Athens, has found 
that spines on an insect's antennae are 
arranged much like the metal rods of a 
TV antenna and receive signals in much 
the same way. The insect antennae, how- 
ever, appear to be far superior to any 
made by man. By studying the antennae 
of insects, scientists may learn how to 
build a better television antenna. 



12 



NATURE A \l> s( II \( I 



SCIENCE] 



WORKSHOP 





# 




(SPIDERS DRAWN ABOUT 
TWICE NORMAL SIZE ) 



\ 



^ft»> 



■ ■■ . .■ -,"T.V \\^ •^'-~ 







Here is how to observe spiders 

spinning webs, catching food, 

and raising their young. 

by Margaret J. Anderson 



■ Spiders live high on mountains and deep in caves, in the 
arctic and in tropical jungles, in dry deserts and even under 
water. Whether you live in a city or in the country, you can 
find live spiders to study. 

Take a careful look at a spider. It belongs to a group of 
animals called arachnids; it is not an insect. You can see 
that it has eight legs and that its body is divided into two 
parts. An insect has six legs and its body is divided into 
three parts. Most adult insects have wings; spiders do not. 
(Some spiders seem to have 10 legs because their mouth 
feelers look like a small pair of legs.) 

Glands in the body of the spider make special liquid 
which is spun out through little tubes (called spinnerets) 
and hardens into silk as it is pulled out of the body. Spider 
silk is used in many ways— for making webs to trap prey, 
for lining nests, for binding prey, and for protecting eggs. 
Perhaps you can discover other uses. 

As a spider watcher you may see some fascinating things. 
You may see a wolf spider scuttling along with her egg sac 
attached to the underside of her body. Carefully pry off 
the egg sac and watch her dart about looking for it. Will 

September 30, 1968 




she accept something roughly the same size and shape 
instead? After the eggs hatch, the female wolf spider car- 
ries the young around on her back until they are able to 
care for themselves. 

Spiders get their food by trapping and hunting insects 
and other small animals. Crab spiders hide among flowers 
and catch insects that visit the flowers. Some crab spiders 
can even change color to match the flowers they are on. 
But if you find a white crab spider living in a white rose 
and move it to a yellow flower, you'll need patience to see 
the result. It takes the spider about a week to change color 
completely. 

Life of the Garden Spider 

A spider that makes a wheel-shaped web (see above) is 
the golden garden spider. It is a big, handsome spider, 
striped yellow and black, and up to an inch long (see 
photo on next page). The spider usually rests clinging up- 
side down to the middle of its web. 

Wait for an insect to tangle in the web (or put one 

(Continued on the next page) 

13 




The golden garden spider builds a strong wheel-shaped web 
in fields and gardens. When you find a web, try to find out 
which parts are sticky and which are not. 

The Ways of a Spider (continued) 

there yourself). Then watch the spider's actions. Spiders 
don't chew their food, although some squeeze and soften 
insects with their jaws. They flood their prey with digestive 
juices which turn parts of the insect into a liquid. Then the 
spider sucks in the liquid, leaving only the insect's hard 




Collecting Webs 



On misty mornings in the fall you can see spider webs 
shining in trees and shrubs. You'll see wheel-shaped 
webs, funnel-shaped webs, tangled webs, and loose trail- 
ing threads. With a little practice you can collect the 
beautiful wheel-shaped webs. 

You will need a spray can of white paint, a spray can 



outer skeleton. How long does a spider spend on a meal? 

Damage the web and see how the spider repairs it. With 
luck you may be able to watch a spider spin its whole web. 
This is sometimes done in less than an hour. 

In the early fall, the female garden spider makes an egg 
sac containing as many as 500 eggs, and then seals it with 
waterproof silk. Her work complete, she spends her last 
days guarding the egg sac, and then dies. Sometime during 
the winter the eggs hatch, but the tiny spiderlings stay safe 
inside the sac until the warm days of spring. If a spiderling 
gets hungry before spring, it simply makes a meal of a 
brother or sister! 

When the spiderlings leave the egg sac they begin to 
explore their new world. Then, after a day or two, they 
crawl up a blade of grass and spin several lines of silk. 
The breeze tugs at the silken threads and the spiderling 
is lifted into the air and floats off to another area. This is 
called "ballooning." The scattering of the young spiders 
helps ensure that each one will have enough food. 

If you find an egg sac in the fall or spring, put it into a 
jar. As the weather warms and the days get longer, watch 
for the spiderlings to hatch. Or you might catch a spider 
in the fall and put it into a jar with a few flower stems. 
Offer it a live fly now and then. If it is a female, and mated 
before you caught it, it will make an egg sac in the jar. 

Once the young spiders emerge you can't keep them all 
together in the jar or they will eat each other. Release the 
spiders and watch them start on their "balloon" journey ■ 



I For more information about spiders, see the book Spiders and 
How They Live, by Eugene David, Prentice-Hall. Inc., Englewood 
Cliffs, N.J., 1964, $2.95. 



of clear varnish, a sheet of construction paper (black or 
a dark color), and a fine brush. First spray paint on the 
web, holding the can at least two feet away. If you are 
too close the spray will damage the web. You may have 
to apply several coats in order to get paint on all the 
strands. While the paint is still "tacky," bring the con- 
struction paper against the web and make sure the whole 
web is touching it. Use the brush to gently break the 
foundation lines of the web at the edge of the paper. 
Then apply several light coats of varnish to seal the web 
onto the paper. 

By collecting several webs, you can compare the ones 
made by different kinds of spiders. You might also try to 
collect several webs spun by a single spider. Collect a 
web every few days and mark the date on the back of the 
construction paper. What changes can you see in the 
webs of a single spider as the spider grows? 



14 



NATURE AND SCIh\< I 



What gives leaves their brilliant 
fall colors? Why does the color 
vary from year to year? Plant 
scientists now have some answers 
to the question of . . . 




How 




■ Every year, as summer days shorten into fall, broad- 
leaved trees begin to change color. In Vermont, where I 
now live, the hillsides are aflame with red, orange, and 
yellow leaves. The colors are so beautiful that many people 
take tours through the New England countryside. Plant 
scientists (botanists) appreciate these colors too, but we 
also ask questions about the colors and about the reasons 
for them. We don't have all the answers, but we have 
learned something about how autumn colors form. 

What Are the Colors? 

Chemists know that there are many kinds of coloring 
matter (pigments) present in leaves. During most of the 
growing season, we see the chlorophylls— green pigments 
that help plants to make food. Chlorophyll is found inside 
roundish bodies called chloroplasts (see diagram) that are 
inside leaf cells. 

Chloroplasts also contain several other pigments. Some 
are yellow. You can see their color in sunflowers, golden- 
rods, and buttercups. In tomato fruits and in carrot roots 
you can see red or orange pigments. All of these yellow, 
orange, and red pigments are called carotenoids. 

There are also small amounts of other pigments in plant 
cells. In the center of many cells is a bag of liquid (the 

Dr. Richard M. Klein is Professor of Botany at the University of 
Vermont, in Burlington. 

September 30, 1968 




Change 
Color 



vacuole) with red pigments inside. One of these is the deep 
red chemical in beet root cells. You can see other red pig- 
ments in red cabbage and radishes. These are called cyani- 
dins. Finally, there are brown pigments called tannins in 
the walls of plant cells. 

Because there is so much chlorophyll in leaf cells, we 
usually don't see the other pigments. They are hidden, or 
masked, by the green chlorophyll. 

But in the Fall... 

When the days begin to shorten in the autumn, the 
amount of chlorophyll in leaves begins to decrease. There 

(Continued on the next page) 



CROSS SECTION 
OF A LEAF 



PALISADE 
CELL 




VACUOLE 
CHLOROPLASTS 

The green coloring of leaves is inside chloroplasts, which are 
most abundant in palisade cells. When the green chlorophyll 
disappears, other pigments in the chloroplasts, vacuoles, and 
cell walls can be seen. 

15 



How Leaves Change Color (continued) 

are several reasons for this loss of chlorophyll, probably 
including some we don't even know about. Some chloro- 
phyll disappears because of the natural aging of the leaves, 
and because of changes in the amount of water available in 
the soil. The shorter days and the cool nights slow down 
the formation of chlorophyll. When the chlorophyll begins 
to disappear, the yellow, orange, and reddish carotenoids 
can be seen. 

This unmasking of the carotenoids causes the fall colors 
of many kinds of trees. The poplar trees in the western 
mountains of North America have leaves which become 
golden yellow. They lose their chlorophyll, and carotenoids 
show through. The fall colors of beech, elm, and sycamore 
trees are also caused by carotenoids. 

When the chlorophyll of oak leaves disappears, carote- 
noids show through. There is also an increase in the 
amounts of tannins. There are already some tannins in the 
cell walls, and more are formed as the chlorophylls break 
down. In years when the autumn colors are dull, the browns 
of the tannins are about all that we see in oak leaves. 



PROJECT 



The amount of light a tree receives seems to have an 
effect on its fall colors. Look for a tree, such as a maple, 
that is close to a street light. How does the extra light 
that the tree receives affect its fall color? 



Some of the most spectacular fall colors are those in 
trees like the sumac and the maples. These bright reds 
are caused by cyanidin pigments in the vacuoles of the leaf 
cells. The most common red cyanidin is called anthocyanin. 
Botanists are trying to find out what causes the large 
amounts of anthocyanin to form. 

There seems to be no one single cause. Warm sunny 
days and cool nights are needed. These conditions favor the 
build-up of sugar in the leaf cells (see "Visit to a Plant 



PROJECT 

Here are some ways to preserve the brilliant colors of 
fall leaves. One is to dip the leaves in melted paraffin. 
(Paraffin should be heated on an electric heater— not 
over a flame.) Dip the leaves in and out quickly so that 
the coating of paraffin is thin. A thick layer of paraffin 
will dull the leaf colors. 

Another way to keep colorful leaves from fading is to 
dry the leaves in warm sand. Put an even layer of clean, 
dry sand on the bottom of an aluminum cake pan. Then 
spread a leaf on the sand and cover it with another 
layer of sand. Set the pan over a 40-watt light bulb, 
keeping the bulb about six inches from the bottom of 
the pan. (The pan can be held up by juice cans or two 
stacks of bricks.) Keep the sand warm, but not hot, for 
about three days. The warmth helps dry the leaves, but 
the colorful pigments are preserved. 



Factory," page 8). Sugar is needed for anthocyanin to 
form. As the chlorophyll begins to disappear, sunlight 
penetrates deep into the cell. The sunlight apparently helps 
anthocyanin to form. 

When Colors Are Best 

The brightness of fall colors varies from year to year. 
For the brightest display, the chlorophylls must disappear 
quickly, the carotenoids must still be plentiful, and the 
anthocyanins must form rapidly. This usually happens at 
the end of a fairly dry period in late summer, followed 
by a crisp autumn with sunny days and cool nights. When 
the fall is cloudy and rainy, the colors are not so bright. 
Knowing this, you can probably predict how bright the 
colors will be in your area this year (if you live in a 
place where broad-leaved trees change color in the fall). 

As the leaves continue to age, there is an increase in the 
brown tannins. Gradually, the yellow, orange, and reddish 
carotenoids begin to disappear, and anthocyanin stops 
forming. Just about this time, the leaves begin to fall from 
the trees and the winter buds harden. Finally, after a hard 
frost, the rest of the leaves die and the tree is prepared for 
its winter rest ■ 



INVESTIGATION 



Collect some twigs that hold several leaves from trees such 
as red and sugar maples, poplars, and oaks. Then try to 
make the leaves turn to their fall colors by setting the twig 
stems in glasses filled with different solutions. You might 
try salt and water, sugar and water, vinegar and water, and 
combinations of these. Place some of the twigs in the refrig- 



erator each night. During the day, put them in sunlight, or 
place them about a foot from a strong (100-watt) light bulb. 
Be sure to put a twig or two in plain water. Then compare the 
results of your experiment with these "control" twigs. 

So far, botanists know very little about how to make leaves 
change color. You may discover something new to science. 



16 



\ <l I Kl I \/> S( 1I.X< I 



r TO A PLANT FACTORY 

view of a tree shows how green plants make their own food from 
. water, and carbon dioxide. The diagram shows the flow of nutrients 
e plant and explains the functions of the taproots, side roots, stems, 
leaves. The vital process of photosynthesis is diagrammed, step by 
This is an excellent teaching aid for introductory units on botany 
ife science. 

/EL GUIDE TO THE SUN AND ITS PLANETS 

,i is a fascinating chart on our solar system. Relative sizes of the 
ets are shown, and descriptive sketches of each planet tell the dis- 
e from the sun, the diameter, the number of satellites, the speed 
nd the sun, the period of revolution, the period of rotation, the sur- 
gravity, and the temperature as estimated by scientists on the earth, 
chart also includes a formula for students to use in determining what 
would weigh on the various planets. 

"SPIRIT" THAT MOVES THINGS 

chart illustrates and explains the concept of energy as a force that 
3 many different forms— light, heat, mechanical, electrical, and chem- 
•nergy, to name a few— and can be stored or used but can never be 
r oyed. Through simple drawings and text, the chart helps children to 
trstand what energy is, where it comes from, and how it is changed 

one form to another. The chart can be used as a basis for classroom 
ission and will stimulate students to look for the countless forms of 
gy in their personal lives as well as in the entire world around them. 

ORY IN THE ROCKS 

lematic drawing of the Grand Canyon in cross-section shows one of 
/orld's unique geologic timetables. The text explains how the canyon 
: ormed and carved by the Colorado River, and simple descriptions tell 
each of the strata was formed. Another section of the chart illustrates 
■ representative fossils of each geologic period. By relating the fos- 
ogether with the type of rock in which they are found, students can 
much about the nature of the prehistoric world. 

3IT ROLLERCOASTER 

unusual chart deals with the annual population cycle of the cotton- 
It is useful in presenting the subjects of ecology, conservation, and 
ral life science. Few rabbits live as long as a year, and the illustra- 
show some of the reasons why— accidents, disease, parasites, preda- 
human hunters, and winter starvation. You can use this chart to 
l many important concepts about the interdependence of all life and 
iroblems faced by animals in their natural environment. 

f DISEASES GET AROUND 

th and science classes gain rich new understanding from this excel- 
chart on disease transmission. Simple diagrams illustrate the 
ading of disease through unpasteurized milk, contaminated water and 
, and airborne viruses. One panel of the chart contains a diagram 
h shows how vaccines protect us from disease by triggering the 
lopment of antibodies in the bloodstream. The chart shows that we 
ot get immunity to the common cold because there are 50 or more 
es that cause it. 

) EATS WHOM 

ecology of the sea and its food cycle are clearly explained in this 
Isomely drawn chart. It explains how animal and plant plankton are 
;eystone in the sea's food chain, and shows how minerals released by 
iecay of dead animals and plants are returned to the food cycle as 
ents for the minute forms of life. The chart can also be used to 
i the structure of various forms of sea life. 

VAYS TO SUCCESS 

nain ways in which plants and animals are adapted to insure the 
irvation of the species are shown in this striking wall chart. The 
ods include frequent reproduction, breeding at an age appropriate to 
fevelopment and life span of the individual, reproduction in vast 
)ers, getting the sex cells together, protection of eggs, and protec- 
of the young. The chart is a useful stimulus for class discussion. 

HORSE'S FIRST 55 MILLION YEARS 

evolution of the horse is a dramatic story that quickly captures the 
ination of everyone. This chart uses museum reconstructions in a 
line presentation to tell that story, and paragraphs of text describes 
eet and teeth of the horse at each major stage in its development, 
chart has excellent applications for introducing units on evolution, 
listorical geology or for explaining the processes of adaptation and 
•al selection. 

IADING THE WORD 

nunication is the subject of this chart, and it tells the story of man's 
of transferring knowledge from one place to another through the 
from the day of the cave man to the present. Fires, drums, smoke 
Is, trail markers, pictographs, writing, movable type, telegraphy, the 
hone, television, and satellite communications are among the many 
ods shown and discussed in this interesting and informative chart, 
leed for greater speed, volume, and accuracy is shown as the cause 
lan's search to find new ways of communicating. 



9 Complete &*J C A 
ection, Just «J> I.DU 



SP 



* 




j/ ROLLERCOASTER \^fc 







tffi& SPIfl T THAT ^ / \ 



KIT™ 



-v- K 




display these colorful charts 
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With the complete set of 10 NATURE AND 
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Imagine your pupils' excitement as each new 
chart is posted on your bulletin board! 



▼ The subject range— disease, communica- 
tion, energy, the solar system— is so varied 
that every youngster will find something of 
interest. And there's no better way to keep 
their interest in science alive at such low cost. 







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WCT-8 



Using This Issue . . . 

(continued from page 2 T) 



together in a substance or object. With 

, simple equipment, they can compare 

i the densities of different substances, 

and from the information given, they 

can make a good guess about the den- 

I sity of the human body. 

Suggestions for Classroom Use 

Have your pupils do their investiga- 
tions at home or in the classroom, then 
compare their findings. 

• To get steel washers nearly equal 
in volume to a stone (Project, page 
10), measure the volume of water dis- 
placed from a full container when the 
stone is gently dropped into it; then 
drop washers into a full container until 
they displace about the same volume 
of water as the stone displaced. 

• In "Sink or Float" (page 10), 
your pupils should be able to guess that 

; the average density of their bodies is 
about the same as that of water, since 

. the body sinks in fresh water but floats 
when its volume is slightly expanded 

\ by taking in air, which is not very 
dense. 

The word "average" is important 

I here, because different parts of the 

: body— bone, blood, organs, etc.— have 
different densities. The same is true of 

j other objects, though, because matter 
is never distributed with absolutely 
equal density through a substance. 
(An atom is mostly "empty space," 
with most of its matter packed into the 
nucleus. A molecule is made of atoms 
connected together with much empty 
space around them.) 

• Your pupils may wonder if den- 
sity is the same as weight density. 
Density is defined as the mass, or 
amount of matter, in an object or a 
sample of a substance divided by its 
volume. By comparing the masses of 
two samples of equal volume, the bal- 
ance and drop tests show which sample 
is denser. To measure the density of a 
sample, we have to weigh it, or mea- 
sure the downward pull of the earth's 
gravity on its mass in terms of the pull 
of gravity on a mass of "standard" 
weight— say 1 lb. or 1 gm. (For a more 
detailed comparison of mass and 



weight, see N&S, Nov. 13, 1967, page 
2T .) Your pupils will see that knowing 
the weight densities of different sub- 
stances is more useful than just know- 
ing which of two substances is the 
denser. 

A number called the specific gravity 
of a substance tells how many times 
denser (or less dense) than water (sp. 
gr. 1 ) the substance is. Your pupils can 
figure out the specific gravities of sub- 
stances in the table on page 10 by di- 
viding their weight densities by the 
weight density of water (aluminum, 
2.7; gasoline, 0.66; and so on). 

Brain-Boosters 

Mystery Photo. The bright marks 
in the photograph of the sun may have 
been made by sunlight that was re- 
flected from a metal surface inside the 
camera to the backs of the eight blades 
of the camera's diaphragm, and from 
there back to the film. The photogra- 
pher doesn't know for sure. 

If you can obtain an unloaded cam- 
era with an adjustable lens opening, 
you can show your pupils what the dia- 
phragm looks like and how it works. 
Open the back and look through the 
lens while the shutter is open. Move 
the diaphragm control dial to various 
positions (or f-stops) to show how the 
diaphragm adjusts to let more or less 
light through to the film. 

Let the pupils decide whether they 
think reflections from the diaphragm 
could have made the bright marks in 
the photo, or whether there could be 
some other way in which the marks 
were made. 

What will happen if? If your pupils 
try this in their bathtubs at home, they 
will see that at first the water squirts 
increasingly farther from the pinhole 
as the balloon gets larger. But as the 
rubber stretches some more, the pin- 
hole gets larger and the stream of water 
smaller. 

If water is released through the neck 
of the balloon, the stream from the pin- 
hole will decrease further. This is be- 
cause the skin of the balloon exerts less 
and less pressure on the water as the 
balloon collapses, and also because the 
rubber around the pinhole has become 
permanently stretched, so that the hole 



will not return to its original si/c. If 
you try the demonstration again with 
the same balloon, the stream from the 
pinhole will never squirt as far as it 
did the first time. 

Can you do it? Give each pupil a 
small amount of a salt-and-pepper 
mixture in a plastic bag, and sec who 
can bring in the separated salt and pep- 
per the next morning. One way to do 
this is to dump the mixture into a glass 
of water. The salt will dissolve, while 
the pepper floats to the top. Another 
way is to run a comb through your hair 
several times, then hold it above the 
mixture. Static electricity will draw the 
pepper to the comb, leaving the salt on 
the table. 

Ask your pupils whether they think 
the mixture can be separated by twirl- 
ing the mixture around in a container 
at the end of a string. (The centrifugal 
effect should force the heavier compo- 
nent of the mixture to the "outer" end 
(or bottom) of the container.) Which 
do they think may be forced to the 
bottom— the salt or the pepper? 

Fun with numbers and shapes. I 
had seven pennies, and you had five. 
Problems like this are easy to make up, 
and your pupils may have some fun 
"stumping" each other with their own. 

For science experts only. The let- 
ters in the secret message are in the 
correct order to give a normal sen- 
tence, but are split up into meaningless 
groups. Regrouping the letters in the 
same order gives:" IF YOU LOOK 
CAREFULLY YOU SHOULD BE 
ABLE TO FIGURE OUT THIS 
MESSAGE. The children might enjoy 
challenging their classmates to read 
messages written in their own "secret 
codes." 

Just for fun. Leave an uncooked egg 
on a table in your classroom to give 
everyone an opportunity to see how it 
resumes spinning after a momentary 
stop. After everyone is satisfied that it 
does, you might place a hard-boiled 
egg on the table, without explanation, 
and see whether anyone can guess 
what happened to this egg to make it 
behave differently from the other. 
Since the contents of the boiled egg 
are solidified, they will stop spinning 
when the shell does. 



September 30, 1968 



7T 



N&S REVIEWS... 

(continued from page IT) 



scries of adventures. His interest ranged 
from whales to dinosaurs. He was for a 
time the Director of The American Mu- 
seum of Natural History, he was the 
author of a dozen books, and he or- 
ganized the first motorized scientific ex- 
pedition into the Gobi Desert in 1922. 
This expedition is probably best remem- 
bered for the discovery of dinosaur eggs, 
but the scientists made many other re- 
markable discoveries. This biography, 
with its lively writing and careful re- 
search, will appeal to many boys and 
girls 12 or older. 

Animal Vision, by George F. Mason 
(Wm. Morrow, 95 pp., $2.95). The sub- 
ject of vision is not a simple one; the 
adaptations of animal eyes seem endless. 
Some mammals (such as rabbits and 
horses) can see behind them while facing 
forward, many animals can see well at 
night, and there is a South American fish 
called Anableps that has two eyes with 
two pupils each — one set of pupils for 
aquatic vision, one for aerial vision. Be- 
fore any of these variations can be 
understood the human eye must be un- 
derstood, so the book first explains the 
anatomy and functioning of the human 
eye. Though the vocabulary is often diffi- 
cult, this should be a useful reference 
book at the junior high level. 

Blood, by Herbert S. Zim (Wm. Mor- 
row, 63 pp., $2.95). This book for 8- to 
12-ycar-olds is a short one, with large 
type and pictures on every page; yet it is 
remarkable how much information is 
packed into it. The introduction is espe- 
cially good, including explanations of 
how life in the ocean utilizes the sea 
water and of how land animals have had 
to become adapted in order to live with- 
out it. Children will learn not only the 
composition of blood, but also the va- 
rious functions of blood, what makes 
blood types different, what happens 
when disease strikes, and how vaccines 
work. The text is clearly written and 
holds the reader's interest to the end. 

Ferns: Plants without Flowers, by Ber- 
nice Kohn (Hawthorn Books, 78 pp., 
$3.75). Many species ol terns are diffi- 
cult to tell apart, and others do not even 
look like ferns. In this hook for 9- to 
12-ycar-olds. children will learn to know 
ihcse species, about a do/en other com- 
monly found ferns, and closely related 

8T 



plants. The life story of ferns is told, and 
there is information on growing ferns, 
both indoors and out. Surprisingly, there 
is no mention of growing ferns from 
spores, an interesting project for chil- 
dren. The drawings are mostly adequate, 
but do not always show the care and 
accuracy needed to complement the text. 

The Remarkable Chameleon, by Lilo 
Hess (Chas. Scribner's Sons, 45 pp., 
$3.25). With its prehensile tail, grasping 
toes, and fantastic turret eyes (swiveling 
independently), the chameleon is a nat- 
ural for a photographer; the photos in this 
book bring out all its oddities. The author 
rightly distinguishes between the true 
chameleon and the little native lizard 
or anole sold as a pet and misnamed 
"chameleon." The main drawback, as 
far as parents or teachers are concerned, 
is the very attractiveness of the photos; 
children may want a chameleon for a 
pet. Fortunately, it is pointed out that 
they are delicate and not easy to keep. 
Directions are given, though, for those 
who still wish to try it. The text is accu- 
rate, and suitable for 8- to 10-year-olds. 

i • ■.-■/ **%„- 





Animals Are Like This and Plants Are 
Like That, both by Irving Leskowitz and 
A. Harris Stone (Prentice-Hall. 64 pp., 
$3.95). These books contain suggestions 
for experiments. Each chapter asks a 
number of related questions on a subject 
and gives the reader considerable infor- 
mation. In the book on animals, most 
ulcas involve invertebrates. (How do 
ants find their way from place to place? 
Can a butterfly tell the difference be- 
tween a sugar and a salt solution'.') In the 
book on plants there are questions in- 
volving such things as enzymes, pig- 
ments, and photosynthesis. The hooks 
give no answers or solutions to the ques- 
tions. Although there are directions for 
performing experiments, they are vague 
or incomplete, assuming considerable 



prior knowledge and experience on the 
part of the reader. The language, too. is 
sometimes difficult. These are books for 
the exceptional child, to be used, in most 
cases, with the help of a science-oriented 
adult. 

The Moon of the Owls, The Moon of 
the Bears, The Moon of the Salamanders, 

all by Jean Craighead George (Thomas 
Y. Crowell, 40 pp. each, $3.25). These 
three slim books are the first in a series 
entitled, "The Thirteen Moons." Each 
follows a seasonal event in an animal's 
life for the space of one month. At times 
there is over-simplification, but the nat- 
ural history is basically sound and the 
writing is excellent. The book on owls 
contains lovely, detailed drawings by 
Jean Zallinger. The illustrations in the 
bear book are decorative, but vague, es- 
pecially those of plant life and insects. 
John Kaufmann's illustrations in the sal- 
amander book are imbued with life and 
capture the feeling of the text. Children 
from the fourth grade up should enjoy 
these books. 

The World of the Ocean Depths, by 

Robert Silverberg (Meredith Press. 156 
pp., $4.95). The hidden land beneath the 
sea is fully as rugged and complex as the 
familiar land above it. There are drowned 
mountains taller than Everest and depths 
reaching down more than seven miles. 
The ocean contains life at all depths, in 
some places in incredible numbers. The 
author presents a comprehensive view 
of the subject, from basic facts to the 
latest theories and ideas for possible fu- 
ture uses of the sea. Ably researched and 
well written, this timely book should 
interest a wide audience of children from 
the sixth made up. 

Karl Patterson Schmidt, by A. Gilbert 
Wright (pub. by M. Evans and distrib- 
uted by J. B. Lippincott. 127 pp.. $3.25). 
As a renowned herpetologist. a trained 
geologist, and an outstanding field nat- 
uralist. Karl Schmidt lived an excep- 
tion, illy full life. From the time he was 
a young student on a Wisconsin farm, 
keeping notes on a captured pine snake. 
to many years later when he sailed as a 
scientist on an important expedition into 
the South Pacific, his life is a fascinating 
story. It makes easy reading for children 
in the filth grade and above. But it seems 
loo bad thai a book about a herpetologist 
should contain misleading statements 
and errors concerning reptiles and am- 
phibians, mostly occurring in a 2 I -page 
appendix on nature projects. 

NATURE AND St II \( I 



nature and science 

TEACHER'S EDITION 

VOL. 6 NO. 3 / OCTOBER 14, 1968 / SECTION 1 OF TWO SECTIONS 

COPYRIGHT © 1968 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 



USING THIS ISSUE OF NATURE AND SCIENCE 
IN YOUR CLASSROOM 



Living with the Aborigines 

Mrs. Gould's delightful account of 
a day with the women of a group of 
Australian desert Aborigines will give 
your pupils some idea of the impor- 
tance of food-getting activities in a 
"hunting and gathering" society. You 
might point out that our ancestors lived 
this way— by hunting, fishing, and 
gathering edible parts of wild plants— 
for thousands of years before they be- 
gan to raise plants and animals for 
food. 

Through class discussion of Mrs. 
Gould's articles and the topics sug- 
gested below, you can help your pupils 
understand how the way in which we 
get our food tends to shape our other 
ways of living. 

Topics for Class Discussion 

• Can you guess why the Bushmen 
of the Kalahari Desert in Africa and 
the desert Aborigines of Australia still 
make their living by hunting and gather- 
ing, instead of by farming and herding? 
So little rain falls in these deserts (less 
than 8 inches per year on the average 
in the Gibson Desert of Western Aus- 
tralia) that these people are hard put 
to find enough water for personal use, 
much less for farming or raising food 
animals. 



MYSTERY OBJECT CONTEST 

Can any of your pupils stump Mr. 
Brain-Booster by sending him an 
object, or photo of an object, that 
he can't identify? See page 12. 



• Why do the desert Aborigines live 
in such small groups and build only 
shade shelters made of bushes? The 
supply of food and water within an 
area that they can cover on foot in a 
day will support only a few people for 
a short time; then they have to move 
to a new area to find more food and 
water. Brush shelters provide some 
protection from the desert sunlight, 
and fires help warm them in the cold 
desert nights; building a more perma- 
nent shelter would be a waste of valu- 
able time. A tent would be just one 
more thing to carry, along with weap- 
ons, tools, and bowls, when they walk 
to a new area. 

• Do you think the desert Aborig- 
ines are "primitive ," or "inferior" to 
other peoples, as they are often called? 
It depends on what you mean by these 
terms. The Aborigines don't have many 
material possessions, but they couldn't 
carry many around with them anyway. 
And finding enough food and water to 
survive doesn't leave them much time 
to make or do other things. Still, as 
Mrs. Gould points out, they have de- 
veloped great skills in finding their way 
around the desert; in making simple, 
easy-to-carry tools that serve many 
different food-collecting purposes; and 
in finding food and water in places and 
ways that other people would never 
think of. Mrs. Gould's lack of these 
vital skills probably made her seem 
"primitive" and "inferior" to her Abo- 
riginal friends. 

The Aborigines also decorate their 

weapons with artistic skill and hold 

(Continued on page 2T) 




IN THIS ISSUE 

(For classroom use of articles pre- 
ceded by •, see pages 1T-4T.) 

• Living with the Aborigines 

This delightful account of their 
food-getting activities raises some 
important questions for your pupils 
to consider {see column 1). 

Not All Boomerangs Boomerang 

A look at the aerodynamics of the 
boomerang — why some fly straight 
and others return. 

The Traveling Seeds 

• How Seeds Get Around 

A Science Workshop investigation 
into seed dispersal and a Wall 
Chart showing some of the forms 
this survival mechanism takes in dif- 
ferent plants. 

• Brain-Boosters 

• What Makes a Drop? 

Your pupils can explore the shape 
and size of liquid drops and find out 
how surface tension holds drops to- 
gether. 

• "Surfing" to Safety 

How the Stenus beetle uses the force 
of surface tension to escape a preda- 
tor that walks on water. 

IN THE NEXT ISSUE 

A special-topic issue explores the 
efforts of scientists to explain the ac- 
tivities inside the earth that cause 
earthquakes, volcanoes, mountain 
formation, and perhaps continental 
drift. 



October 14, 1968 



Using This Issue . . . 

(continued from page IT) 

fairly elaborate ceremonies honoring 
or appeasing the "spirits" of the ani- 
mals and plants that they depend on 
for survival. Their rules for such cere- 
monies, for deciding who can marry 
whom, for getting along with other 
groups of Aborigines, and so on, are 
just about as complicated as our own 
rules about such things. 

• You can see that the desert Abo- 
rigines' life is shaped almost com- 
pletely by their way of getting food. 
How does our way of getting food af- 
fect our lives? The "invention" of farm- 
ing and herding about 10,000 years 
ago gave men a more reliable source of 
food; made them settle in one place in- 
stead of roaming around in search of 
food; and freed some people from 
food-getting work. This led to the be- 
ginnings of what we call "civilization" 
(see "When Men First Learned To 
Farm'/N&S, Nov. 14, 1966). 

In the United States, modern farm- 
ing machinery and methods enable less 
than 10 per cent of the people to pro- 
duce enough food for the entire popu- 
lation, freeing the others for activities 
such as manufacturing, building, edu- 
cation, the arts and professions, enter- 
tainment, and so on. Rapid transporta- 
tion of food over long distances; pre- 
serving foods by canning, freezing, and 
other processes; and distributing foods 
in packages through stores all over the 
nation— these things make it possible 
for people to live just about anyplace 
they wish, instead of in or near a place 
where food is raised. 



NATURE AND SCIENCE is published for The American 
Museum of Natural History by The Natural History 
Press, a division of Doubleday & Company, Inc., fort- 
nightly September, October, December through March; 
monthly November, April, May, July (special issue). 
Second Class postage paid at Garden City, NY. and at 
additional office. Copyright © 1968 The American 
Museum of Natural History. All Rights Reserved. Printed 
in U.S.A. Editorial Office: The American Museum of 
Natural History, Central Park West at 79th Street, 
New York, N.Y. 10024. 

SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester 
per pupil, $1.95 per school year (16 issues) in quanti- 
ties of 10 or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's 
edition $5.50 per school year. Single subscription per 
calendar year (17 issues) $3.75, two years $6. Single 
copy 30 cents. In CANADA $1.25 per semester per 
pupil, $2.15 per school year in quantities of 10 or more 
subscriptions to the same address. Teacher's Edition 
$6.30 per school year. Single subscriptions per cal- 
endar year $4.25, two years $7. ADDRESS SUBSCRIP- 
TI0N correspondence to: NATURE AND SCIENCE, The 
Natural History Press, Garden City, N.Y. 11530. Send 
notice of undelivered copies on Form 3579 to: NATURE 
AND SCIENCE, The Natural History Press, Garden City, 
N.Y. 11530. 



(You might point out that while 
nearly all peoples get their food by 
farming and herding today, the lack of 
good soil, fertilizers, and modern ma- 
chines and farming methods keeps 
people in many countries from being 
able to feed themselves adequately. 
Also, no one knows whether farming 
and herding— on the land and even in 
the oceans— can supply enough food 
for all of the earth's rapidly increasing 
human population.) 

• How does the desert Aborigines' 
way of getting food affect their natural 
environment— the soil, water, air, 
plants, and animals where they live? 
When the Aborigines leave an area (to 
search elsewhere for food), the soil 
and air have not been changed at all; 
in time, the living things grow back, 
and the water is replenished. By living 
with their natural environment, the 
Aborigines have survived for thou- 
sands of years. 

• How does our way of getting food 
affect our natural environment? Farm- 
ing changes the natural environment 
irreversibly. The natural cover (grass, 
forests, rocks, etc. ) must be removed 
from land to raise crops on it. (Over- 
grazing by herds of animals often de- 
stroys the cover in dry areas.) Rain- 
water that would be held in the soil by 
the natural cover tends to run off the 
"uncovered" land swiftly, carrying part 
of the topsoil along with it (and some- 
times producing floods). In dry sea- 
sons, strong winds also carry away dry 
topsoil. (The topsoil, formed over mil- 
lions of years, is only 2 to 5 feet deep 
in farming areas of the U.S.) 

Building dams and canals to irrigate 
dry farmlands slows up the flow of 
water in streams, making them drop 
silt that eventually chokes up the dams 
and canals. Pumping water from wells 
uses up the ground water faster than 
it is replenished, and often lets salty 
water seep into the ground water sup- 
ply. 

Fertilizers washed from farmlands 
into lakes increase the growth of water 
plants that choke off life in the lakes 
(see "How To Kill a Lake," N&S, Apr. 
1 , 1968). Raising one kind of plant on 
acres of land encourages insects that 
feed on that plant to grow in numbers, 
sometimes to "plague" proportions. 
Biocides— chemicals used to kill weeds 



and insects— drift in the air and wash 
into the soil and water, poisoning many 
fish, birds, and other animals. 

Even the highways, railroads, ware- 
houses, factories, and stores we build 
to carry, process, and sell foods often 
destroy natural cover and expose top- 
soil to erosion (wearing away by wind 
and water). Trucks, trains, and ships 
that carry our food supplies help pol- 
lute the air and oceans with fumes and 
oil wastes. 

We are just beginning to understand 
that in changing our natural environ- 
ment to produce more and more food 
for more and more people, we may be 
endangering the food supplies, the 
health, and perhaps even the survival 
of future generations. 

• Do you know of any edible plants 
and animals that grow wild in your en- 
vironment? This will be a hard ques- 
tion to answer, for reasons that merit 
discussion: 1) Where many humans 
live, there is usually very little wildlife 
left. 2) Our food habits make some 
things seem inedible that would be 
considered delicacies by people who 
live by hunting and gathering. 3 ) Lack- 
ing the need to recognize and find 
wild foods, few people today learn how 
to do it. 

Your pupils may think of a few 
things, such as nuts, berries, and dan- 
delion greens, but they will probably 
realize that the amount of such foods 
in their area would not feed many 
people for very long. 

One of your pupils might read and 
report to the class how a man and his 
wife managed to survive for two weeks 
on an uninhabited island in Lake Su- 
perior by hunting and gathering food. 
This fascinating and revealing adven- 
ture is related in a two-part illustrated 
article, "Desperate Vacation," by Pat- 
rick K. Snook, in National Wildlife 
magazine for February-March and 
April-May, 1968 (available at some 
libraries or possibly from a member 
of the National Wildlife Federation, 
which publishes the magazine). 

How Seeds Get Around 

The dispersal of plants and animals 
is often essential to their continued ex- 
istence. Point out to your pupils that 
(Continued on page 3T) 



2T 



NATURE AND SCll \< I 




VOL. 6 NO. 3 / OCTOBER 14, 1968 



and science 



Mre an aropb oi wciier me 
same shape and size? 
You can find out what 
holds them together. 

see page 13 

WHAT MAKES A DROP? 









Most plants are 

"stick-in-the-muds," 

but their seeds are "born 

travelers": some go by air, 

some by land or sea, and some 

are even hitchhikers." 

see pages 7 and 8 

THE TRAVELING SEEDS 

and 
HOW SEEDS GET AROUND 



rt iJVfii-iivL. nuv t_ i i i w i 



nature and science 

VOL. 6 NO. 3 / OCTOBER 14, 1968 

CONTENTS 

2 Living with the Aborigines, Part 2, 

by Elizabeth B. Gould 
5 Not All Boomerangs Boomerang, 

by Harry Butler 

7 The Traveling Seeds, by Nancy M. Thornton 

8 How Seeds Get Around 

1 1 Brain-Boosters, by David Webster 

1 2 Mystery Object Contest 

1 3 What Makes a Drop?, by David Webster 

1 5 "Surfing" to Safety, by Anthony Joseph 

1 6 What's New?, by Roger George 



PICTURE CREDITS: Cover, p. 7, © 1968 Arline Strong, from Lions in the 
Grass, World Publishing Co.; pp. 3, 4, 6. photos by Richard A. Gould; p. 5, 
Harry Butler; pp. 6, 8-11, 14, 15, drawings by Graphic Arts Department, The 
American Museum of Natural History; p. 10. photos by David Linton; p. 11, 
photo by Betsy Harding; p. 12, Victor Stokes; p. 13, Simon Siflinger; p. 15, 
photo by N. E. Beck, Jr.. from National Audubon Society; p. 16. (left) United 
Press International, (right) The American Museum of Natural History. 



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* 




by Elizabeth B. Goulc 






■ When we got to Warburton Ranges, we found only \ 
small church mission where Aborigines often camp ana 
get some food supplied by the Australian government 
Sometimes, though, they go off in groups of a dozen or so 
to live in the Gibson Desert as their ancestors did. 

We spent about seven months, altogether, living mm 
the Aborigines out in the desert. We found that the moa 
important things in these people's lives are food and wata 
—especially when they are trying to survive in the deserl 

We tasted the food that our friends offered us (see photo, 
but mostly we lived on the food wc brought in cans, 
wouldn't have been fair to expect them to feed us, becaul 
finding enough food and water to keep themselves alivi 
takes most of their time and energy. 

The Daily Search for Food 

When morning comes, an Aboriginal woman of the desj 
ert knows she will have to spend much of the day gathering 
food for her family. She cannot reheat yesterday's "left 
overs," because there is probably no more than a crust q 
seed cake or a kangaroo's head with a few shreds of mefl 
clinging to it left from yesterday's meal. And she cannq 
depend on her husband to bring home a freshly-killcc 
kangaroo or emu bird; such a large animal is a rare treat 

The women leave camp in small groups while the morn 
ing coolness is still in the air. Often I would go along witj 
them while they gathered food. One night some of thi 
women told their friends that they had found large arc.i: 
of a ripening seed called wangunu. They had filled the! 
bowls with it, but there was plenty left for several nion 

VATURE AND SCIENl 



h the last issue, Mrs. Gould told 
;ow she and her husband, an 
Anthropologist at The American 
luseum of Natural History in New 
,ork City, made friends with a 
'Iroup of native Australians who 
'ere living on a government 
sservation. The Goulds began to 
isarn the language of these 
'eople and something about their 
'ay of life. Then they drove 
eeper into the desert to find 
! ut how some Aborigines live 
1 the way their ancestors 
ved for centuries. 




Mrs. Gould samples yawalyuru berries picked by an Aborigine in the Gibson Desert. 
These people roam the desert in small groups, getting most of their food by col- 
lecting small animals and the edible parts of wild plants. 



ays' collecting. So the women started off early the next 
iorning, each with her digging stick and a wooden bowl, 
! she had one. The small children tagged along; some were 
icky enough to get a ride on their mothers' backs. 
On the way to the wangunu seed, everyone kept a sharp 
tokout for other food. Sometimes they saw a tree bearing 
few hard, round, green fruits called kalkurlci. Often they 
bpped berries or fruits into their mouths as a "snack" as 




they walked along. One of the women saw some fresh 
goanna (lizard) tracks, and she went off to follow the 
goanna to its burrow and dig it out. 

When they reached the wangunu plants, each woman 
stooped and put her wooden bowl at the base of a clump 
of plants, which stand about two feet high. Then she shook 
the stalks so the heavy heads of grain fell into her bowl 
(see photo). She walked back and forth, looking for good 
stalks of ripe wangunu. When her bowl was filled, she sat 
down in a clear spot and tossed handfuls of seed into the 
air to let the breeze blow away the chaff. 

Trailing Tasty Treats 

The women look for many kinds (species) of small mar- 
supials, or mammals with pouches to hold their young, that 
are native to Australia. They also look for other animals 
such as rabbits, mice, and cats that have spread in the wild 
since the Europeans brought them to Australia. All of 
these are considered tasty treats by the Aborigines. 

Women who are out gathering food don't simply wander 
from place to place hoping that there might be something 
across the next sand ridge. They know where they are 
going and what they expect to find. I was often amazed at 
how easily these women read the tiny signals that pointed 

(Continued on the next page) 



An Aboriginal woman spends her mornings gathering food, 
the afternoons preparing it. The top photo shows a woman 
collecting seeds from wild wangunu plants. At the left, she is 
shown making cakes of kampurarpa seeds. 




1 i v 'lliii y jt/Llhe Aborigines (continued) 



to food. Tracks in the sand that were almost invisible to me 
told them a whole story about the animal that had passed 
that way: how big it was; when it had been there; which 
way it was going. And this might tell them which waterhole 
the animal would visit next. 

It wasn't that I couldn't see these clues; I just didn't 
know what to look for. I had been brought up to use such 
things as clocks and traffic lights to get along in my world; 
these people had learned from early childhood to read 
messages in the landscape with astonishing accuracy. As 
time went on, I understood more, but it was always a great 
joke to the Aborigines that, if left alone, I would probably 
die in the desert, even though I was surrounded by clues 
to food and water. 

These women know the location of every nearby water 
hole, and they take care not to go too far away from one. 
They know their country so well that they can distinguish 
between different sand-hills and groves of trees that all 
looked the same to me. (Sometimes it seemed as if each 
tree had its own personal name!) 

Once when I was out with several women, one of them 
saw a mulga tree that was shaped just right for a spear- 
thrower to be cut out of its bark. Women never use or 
make spears and spearthrowcrs, but their husbands arc 
always looking for good raw materials. When we got back 
to camp, this woman told her husband about the spear- 
thrower tree in such great detail that he was able to go 
straight to that tree. Women also tell their husbands about 
any fresh kangaroo tracks they may see, for kangaroo 
hunting, too, is men's work. 

By mid-afternoon most of the women are back at camp. 
It is too hot to walk around in the sun, and they have work 
to do in camp. They cook the small animals by roasting 
them in hot coals. They grind up the seeds into flour and 
make cakes which arc also cooked in hot coals. Some- 
times one of the men may bring home a kangaroo or emu 
bird, and then they will all share in the feast. But this is 



Seated at her desert "oven," an Aborigine re- 
moves the meat course for the afternoon meal- 
roast lizard— from a bed of hot coals. 



unusual, for most of the time the hunters return empty- 
handed or with only a few lizards tucked into their hair- 
string belts. 

Food and a Woman's Pride 

Since food is not always plentiful in the desert country, 
the Aborigines' diet is pieced together from many different 
kinds of plants and animals. This variety is helpful, be- 
cause the Aborigines do not have to depend on any one 
species of plant or animal for food to survive. 

Because it is so scarce, however, food is one of the major 
topics of conversation around the Aborigines' camp. A 
woman knows she is providing most of her family's food, 
and she is proud of it. If she comes back at the end of the 
day with several rabbits dangling by their ears from a 
stick, her skill will be the talk of the camp. 

She hates to go home empty-handed, though. I can re- 
member waiting impatiently when it was time to return to 
camp and the women would not give up looking. They dig 
in the sun for hours, perspiration dripping from their heads 
and their damp hair hanging in strings. They move enor- 
mous quantities of soil, sometimes digging down until they 
are almost out of sight. If the burrow is empty when they 
reach its end, they are very disappointed. 

But if a woman has a bad day. only her pride will 
suffer. She knows that her relatives will not let her chil- 
dren starve ■ 







Kangaroo meat is a rare treat for the desert Aborigines. The 
carcass is buried in hot coals, and roasts until they cool, 
leaving the meat very uncooked, by our standards. 



\ 4TURE A\'D S( II \( I 




NOT ALL BOOMERANGS 



Different kinds of boomerangs were important tools 
Aborigines living in the wilds of Australia. Here is 
how some boomerangs, including the famous return 
kind, were used by the Aborigines. 

■ We use the word "boomerang" to describe something 
that returns to its sender. An object (or a remark) that 
returns is said to "boomerang." But oddly enough, very 
few real boomerangs ever come back. There are many 
kinds of boomerangs and only one kind is designed to 
return when you throw it. 

Boomerangs were invented by the Aborigines of Aus- 
tralia (see page 2). They were first used as throwing 
weapons for killing small animals and perhaps for fight- 
ing. The Aborigines had few tools. They wore little or no 
clothing, and had no pockets, so every object they carried 
had to be useful in many ways. A boomerang could be 
used for hunting, fighting, digging, cutting, starting a fire, 
and for making music. Only one kind of boomerang, made 
and thrown in a special way, would circle and come back 
(see "Why a Boomerang Returns," on the next page). 

Boomerangs for Hunting 

The Aborigines used three kinds of boomerangs for 
hunting. One was a club that was used mainly for hunting 
emu, bustard, and other long-legged birds. It was thrown 
overarm, straight at the animal. It would spin in flight but 
didn't return. 

Another hunting boomerang that didn't return was 
much lighter and a little smaller, and was used for killing 
fish in shallow water, and birds such as parrots, pigeons, 
and ducks. It was normally used with the third type of 
hunting boomerang— the famous returning kind. 

To hunt ducks, a group of Aborigines would surround a 
pond, and on a given signal, most would stand and throw 
a non-returning boomerang into the flocks of ducks sitting 
on the water. The boomerangs would slice across the sur- 
face and kill or injure many birds. Of course, the other 
ducks would start to fly away. At this moment a few men 
would throw their returning boomerangs above the rising 
ducks. At the same time the men would imitate the call of 
the duck hawk. The flock, seeing the circling forms above 
them and hearing the call, would dive low to the water or 
earth to escape the expected attack of a hawk. Then the 
hunters would throw more "killer" boomerangs. 

Sometimes the hunters spread their nets between tall 

October 14, 1968 



for 

ing 



The two boomerangs shown above 
are for hunting; A is for fish, 
B for land animals. C and 
D (below) are both 
shaped to return. 




trees, then threw returning boomerangs high into the air. 
This frightened flocks of birds into the nets, where they 
were caught and clubbed. 

Even today young people in Australia use a kind of 
boomerang for killing mullet, salmon, herring, and other 
fish. They use a "kylie"— a piece of iron about 18 inches 
long that is folded and flattened until it forms a V with an 
angle of about 40 degrees. In the summer, people hurl 
kylies at schools of mullet in the shallow water of the 
Indian Ocean. The mullet flee from the splash, but then 
they immediately return to examine the spot where the 
splash took place. At that moment the fishermen throw 
another kylie at the same spot. The word "kylie" is the 
name given to a hunting boomerang used by Aborigine 
tribes of Southwestern Australia. 

Although Aborigines sometimes had fierce battles, they 
were not fighting men in the way many of the American 
Indian tribes were. The club-like hunting boomerang was 
used in fights. Some of the men threw their boomerangs 
flat so that they spun sideways through the air. Others 
threw the boomerangs at the ground so that they bounced 
up and struck the enemy. In close fighting, boomerangs 
were held by their handles with the sharp edge facing the 
enemy and were used like an axe. The fire-hardened edge 
could be very dangerous. 

In peaceful day-to-day living, a boomerang might be 
used to dig a lizard from its hole in the ground, or to start 

(Continued on the next page) 



[Sot All Boomerangs Boomerang (continued) 

a fire. The Aborigines sometimes made fire by rubbing the 
hard edge of the boomerang across a groove in the center 
of a soft wood shield. I have seen fire made within 30 
seconds in this way. 

Aborigines also used boomerangs as picks and shovels. 
To build a new home, a man would first break off branches 
from a mulga tree. Then he would drive the end of his 
boomerang into the sand, wiggling and twisting it to make 
a hole in which to put a tree branch. One by one, more 
branches were stuck in the ground in this way until they 
formed a seven-foot-wide circle, with the tops of the 
branches touching. More branches were then woven into 
this framework. The earth inside the circle was loosened 
and shoveled with the boomerang, forming a pit below 
ground level, out of the wind. 

Some Boomerangs Return 

Since Australia was settled by people from Europe, the 
old tribal systems of the Aborigines have been broken up. 







This desert Aborigine showed Dr. Gould (see page 2) how to 
make a boomerang from a curved tree limb, though his own 
people do not usually use these hunting weapons. 

Nearly all of the Aborigines now live in reserves or at 
missions. The children go to school and eventually be- 
come Australian citizens. But the parents cannot or will 
not change, and live their old life as much as possible. 

One of the sports that they play is boomerang throwing 
—the art of hurling a returning boomerang and watching 
as it whizzes in a great circle and then returns to the 
thrower's hands. Recently at a mission I watched an 
Aborigine throw seven boomerangs, one after another. 
The seventh had left his hand by the time the first one was 
returning. He was able to catch six out of seven, and I 
think he would have caught the seventh if his attention 
hadn't been distracted.— Harry Butler 




A returning boomerang travels in a circle, back to its 
thrower, for the same reason that an airplane flies. 
As an airplane is pushed forward by its engines, air 
flows over the surfaces of its wing. The upper surface 
of each wing is curved, so the air rushes over this 
surface faster than it does over the flat lower surface 
(see diagram). Because the air moves faster, it 



CROSS SECTION OF 
AIRPLANE WING 



CROSS 
SECTION OF 
BOOMERANG 



AIR STREAM 




PUSH OF AIR 

-* 



presses down less on the upper surface than it does 
on the flat lower surface. The greater pressure on 
the lower surface of the wing tends to push the wing 
upward. 

A returning boomerang also has a flat surface and 
a rounded surface. If you threw a boomerang hori- 
zontally, like an airplane wing, it would go straight 
and would rise in the air as an airplane does. But 
when it is held and thrown vertically (see diagram), 




the air pushing on the flat surface makes the boom- 
erang turn in the direction of its curved surface. The 
stronger the throw, the farther the boomerang will 
circle. 

You can buy boomerangs in some toy shops and 
department stores. Some of these are poorly made 
and won't return no matter how you throw them. If 
you do try to throw a returning boomerang, be sure 
to practice in a big open field and keep a good dis- 
tance from other people. If you succeed in having 
a boomerang return, you have one more problem: 
stopping it. Even Aborigines sometimes hurt them- 
selves when they try to catch a fast-moving, spinning 
boomerang. Just let the boomerang fall to the ground. 



^ 



NATURE ANDSCIENi I 




Autumn is a good time to 
investigate the ways 
in which different plants 
scatter their seeds. 
Here is how you can go 
about studying.. . 



The 

Travelin 
Seeds 

by Nancy M. Thornton 




A head of dandelion 

seeds, each with its own 

wind-catching "umbrella," is 

fascinating to look at and fun 

to blow (see cover). 






■ More weeds in the garden! No one planted dandelions 
and burdocks among the roses, yet there they are. How 
did they get there? 

Dandelions and burdocks are just two kinds (species) 
of plants that have evolved special ways of scattering their 
seeds. Plant scientists (botanists) call this seed dispersal. 

The scattering of seeds is one way that a species of plant 
has of ensuring that it will survive. If all of the seeds 
dropped directly below a parent plant, many might not 
sprout. Those that did sprout would compete with each 
other, and with the parent plant, for sunlight and moisture. 
When the seeds scatter away from the parent plant, how- 
ever, they have a better chance to sprout, grow, and pro- 
duce seeds of their own. (For illustrations of the ways some 
common plants scatter their seeds, see pages 8 and 9.) 

Flying and Floating 

You can probably find many examples of seed dispersal 
in your neighborhood. You might want to make a collec- 
tion or display of the seeds you find. Collect a twig of the 
plant with some leaves on it along with the seeds. Dry the 
twig and leaves between sheets of newspaper with a weight 

October 14, 1968 



to press them flat, and put them in a cellophane envelope 
with the dried seeds. Make a label with the plant's name 
and the seed dispersal method. If you don't know the name 
of the plant, take notes on its height, appearance, and other 
characteristics. This information, with the leaves and seeds 
you collected, will help you identify the plant. 

Look for mature seeds on the plant. They should be firm 
on the outside, and the inside should not be green or milky. 
Sometimes, of course, the seed will be part of a fruit, such 
as a berry. 

Seeds are scattered by wind and water, and by animals 
such as birds, insects, and mammals, including humans. 
When you look at mature seeds you may find special parts 
that help them travel. If a seed is to be carried by the wind, 
it usually has some structure that enables it to float or spin 
in the air. Look for fluffy "parachutes" or some sort of 
"wings." Some seeds are carried by the wind because they 
are as tiny and lightweight as a speck of dust. 

The seeds of many plants that grow near oceans are 
spread by water. A cocoanut seed, enclosed in a light- 
weight, water-tight husk, may float for hundreds of miles. 

(Continued on page 10) 




'-^C&u^ 





Seeds with "wings" spin or 
sail away from their parent 
plants. 



When the tough seed pods of 
milkweed split open, about 
100 seeds with silky "para- 
chutes" begin to drift away 
through the air. 





^ For a kind (species) of i 

produce young and the you 

offspring of their own. I 

plants and animals havi 

different ways of pr 

Among plants, th< 

parent plant is an ini 

of the species. Th 

Chart show som 

seeds are seal 

where their c 

and growing 

show detail 

around, 

plants ; 

drawn 



t 



^jf 






% 







Squirrels and chipmunks often forget 
where they hid nuts and acorns. Later 
these seeds may sprout and grow. 



PEARLWORT 

Rain drops splash 
seeds out of the seed 
containers of the pearl- 
wort plant. 




VETCH 

When the s 
plants dry, tl 
snap apart v 
tion, tossing 

BEGGAR T JKS— Seeds w 
onto fur 
They m 
miles be 
the grou 




• animal to survive, it must 
jt live long enough to have 
iany thousands of years, 
\r developed, or evolved, 
r t young successfully, 
ring of seeds from a 
:, help in the survival 
ings on this Wall 
ways in which 

o new places 

of sprouting 
fc better. (To 
w seeds get 
1 of the 
|>ds 
He.) 



The seeds of many fruits are 
protected by tough coatings. 
When birds and mammals eat 
the fruits, the seeds are not 
digested. They pass out of the 
animals' bodies as waste, per- 
haps miles from where the 
fruit was first eaten. 



WITCH HAZEL 





Some seed containers sud- 
denly pop open and shoot 
seeds in all directions. Witch 
hazel seeds may travel 10 feet 
or more. 



i of vetch 
i half and 
sting mo- 
away. 



natch 
thing. 
t\ for 
ig to 




The umbrella-like tops of dandelion seeds have 
helped spread this plant around the world. 



Some seeds have bristles that spread apart 
and then close as the amount of water vapor 
in the air varies. This movement of the bristles 
makes the seeds creep slowly along the sur- 
face of the ground. 



CRIMSON CLOVER 




When the seed capsules of wild gerani- 
ums dry out, a spring-like device re- 
leases them and the capsules snap 
outward, throwing seeds away from the 
plant. 



Even without "wings' 
and "parachutes," 
some seeds are so 
tiny and lightweight 
that they are carried 
by the wind. 




A seed grows from the tip of the red mangrove plant's fruit 
(left). When it is about a foot long, it drops and takes root 



there (center) or floats in the water until it takes root and 
grows into a tree (right). 



The Traveling Seeds (continued) 

Raindrops sometimes help seeds of land plants to scatter; 
the drops splash seeds of a plant called pearlwort out of 
their containers in the plant. 

Taken for a Ride 

Many seeds that are inside fruits are spread by animals. 
A bird may eat the fruit and then drop the seed to the 
ground. Or the whole fruit may be swallowed. Then the 
seed may travel unharmed through the bird's digestive tract 
and pass out of its body miles from where it was first eaten. 

Recently a Texas biologist, Dr. Vernon Proctor, decided 
to find out how long seeds can stay within the bodies of 
some caged birds and still be able to sprout. He found that 
the seeds of some water plants would still sprout after being 
inside ducks and shorebirds for as long as 100 hours. One 
bird, a killdeer, carried a sumac seed in its body for 340 
hours. If the birds had been free to fly, they might have 
carried the seeds thousands of miles. 

Even as you walk in a field looking for different ex- 
amples of seed dispersal, you may be helping plants scatter 
their seeds. Check your clothes to see if any seeds have 
become "hitchhikers." Many seeds have hooks, barbs, or 
spines that catch on clothing, fur, or feathers. Take a 
magnifying glass along and look at the seeds of burdock, 
beggar-ticks, and cocklebur to sec how the seeds "hitch 
rides" (see diagram). 

OPENED COCKLEBUR 
SHOWING 2 SEEDS 

HOOKED SPINE 

When you look at some plants you'll be able to tell at 
a glance their ways of seed dispersal. Others will be more 
difficult to guess at. Some' plants, for example, have seed 





capsules that help scatter the seeds. When the capsule dries, 
it suddenly splits open and the seeds are tossed out. In other 
plants, water pressure or spring-like devices send the seeds 
zooming through the air to land several feet from the parent 
plant. 

Look for these kinds of seed capsules on such plants as 
witch hazel, jewelweed, and violet. If you find a plant that 
is scattering its seeds, measure the distance a seed travels 
from the plant. Do this for several seeds (including some 
from different seed capsules). How far is the average seed 
thrown from the plant? 

This is just one question about seed dispersal that you 
can investigate. Some other investigations are listed on this 
page, along with some helpful books ■ 

I For more information about seed dispersal, see these well- 
illustrated books: The Amazing Seeds, by Ross Hutchins, Dodd. 
Mead & Company, New York, 1965, $3.50; Play with Seeds, by 

Millicent Selsam, Wm. Morrow and Company, New York. 1957, 
$3.14. 



INVESTIGATIONS 

• Plants that die after one growing season are 
called annuals; those that live for several growing 
seasons are called perennials. Compare the ways of 
seed dispersal of several annuals and perennials. 
Does one group have a greater ability to scatter its 
seeds? Why? 

• Observe some wind-carried seeds to see how 
far they travel from a plant before settling to earth. Is 
this the end of their journey? 

• Compare the ways of seed dispersal of wild 
plants with those of domestic plants, such as garden 
vegetables and flowers. Are there any garden plants 
whose seeds seem to be spread only by humans? 
What problems might seed dispersal present to grow- 
ers who produce seeds for use on farms? 



10 



\ ITVRE A\n SCIENCE 




Mystery Photo 

What is it? Submitted by Betsy Harding, Ithaca, New York 



Can you do it? 

Can you swallow some water while you are upside down? 

Fun with numbers and shapes 

How many times in 12 hours does the minute hand of a 
clock pass the hour hand? 



For science experts only 

If you placed a yardstick on a table so that half of it ex- 
tended past the edge of the table, and then you hit the 
unsupported end of the yardstick sharply with the edge of 
your hand, the yardstick would fly across the room. But if 
you placed a sheet of newspaper over the part of the yard- 
stick that is on the table (see diagram), the yardstick would 
probably break when you hit it. Can you figure out why? 



prepared by DAVID WEBSTER^ t~ 



What would happen if? 

Which path would 
the marble follow 
after it left the plate? 



PAPER PLATE 




Just for fun 

Drop some pepper or tiny pieces of paper towel into a glass 
of hot water. Then put in an ice cube and watch the pepper 
or paper bits move around through the water. The cold 
water from the melting ice cube is denser than the hot water 
(see "How Dense Are You?," N&S, September 30, 1968), 
so it sinks to the bottom, making a current as it moves. 



ANSWERS TO BRAIN-BOOSTERS IN THE LAST ISSUE 



Mystery Photo: The photographer thinks that the bright 
marks in the photograph of the sun may have been made 
by sunlight that was reflected from a metal surface inside 
the camera to the backs of the eight metal blades of the 
camera's diaphragm, then back to the film. Can you figure 
out any other way that the bright marks may have been 
made? 

What will happen if? The water from the hole in the balloon 
at first squirts farther as the balloon gets larger. When 
the rubber stretches more, however, the pinhole becomes 
larger and the stream of water decreases. What will happen 
to the stream from the pinhole as water is released from 
the balloon through its "mouth"? 



Can you do it? One way to separate the pepper from the 
salt is to dump the mixture into a glass of water. The salt 
will dissolve, while the pepper floats on top. Another way 
is to use static electricity. Run a comb through your hair 
several times, and then hold it close to the mixture. The 
pepper should fly up and stick to the comb. 

Fun with numbers and shapes: I had 7 pennies and you 
had 5. Suppose we had 12 pennies altogether and you 
had twice as many as I had. How many would you have? 

For science experts only: The secret message was: IF YOU 
LOOK CAREFULLY YOU SHOULD BE ABLE TO FIGURE 
OUT THIS MESSAGE. 



October 14, 1968 



11 



Do you 
know 
what any 
of these 
things are 
used for? 




MYSTERY OBJECT CONTEST 



This year, instead of a Brain-Booster Contest, we are 
having a Mystery Object Contest. Can you find something 
that I am unable to identify? You can either mail the thing 
to me or send me a photograph of it. Your Mystery Object 
can be something that you buy in a store or something you 
find outdoors. 

I will write to everyone who enters the contest. If I know 
what your Mystery Object is, I'll give you the answer. If 
I don't know, I'll have to write and ask you to tell me. A 
$10 award will be made to each of the 10 readers who 
submit the best Mystery Objects. 

To enter the contest, send your object or photograph to: 
Mr. Brain-Booster 
Bedford Lane 
Lincoln, Mass. 01773 
12 



Entries must be mailed by November 15, 1968. Be 
sure to give your address, age. and grade in school, or 
tell me if you are an adult. We will publish the names of 
the winners and some of their entries in the February 17, 
1969 issue of Nature and Science. 

I'll bet you can't stump me 



/j^.^ 



P.S. The Mystery Objects shown in photos on this page are: I. A hook 
used for tightening boot laces, 2. A screen thai is placed in the top of 

a rainspout to keep leaves out. 3. Shell macaroni for cpoking and eat- 
ing. 4. An archery finger guard, for protecting the fingers when shoot- 
ing a bow. 5. A holder for toasting four pieces of bread on a gas stove. 



NATURE AND S( II \( I 




RAM 
©SOP? 



Drops of liquid do strange things. With a medicine 
dropper, some water and cooking oil, and a piece of 
aluminum foil, you can find out a lot about them. 



BY DAVID WEBSTER 



■ Drops come in many shapes and sizes, and they do 
things that may surprise you. Take a glass of water out- 
doors and throw the water up into the air. You will see 
that some of the water forms drops. Are all the drops the 
same size? Now try to throw the water higher to see if 
more drops are formed. 

Have you ever wondered why water makes drops? 
Why not do some experiments to find out more about 
them? All you need is a piece of aluminum foil or wax 
paper, and water. Wet your hand and sprinkle some water 
onto the aluminum foil. Now you have drops which you 
can study. Bend over so you can look at the drops from 




_^> 




d*> 



October 14, 1968 



the side. Which ones are rounder, the small ones or the 
larger ones? Can you figure out why some water drops 
are rounder than others? 

You can move your drops around with a pin or paper 
clip. Push two or three small drops together to make a 
bigger drop. Then take two pins and try to pull the bigger 
drop apart to make two smaller ones. Does the drop seem 
to stick together? 

Drops Have Elastic Skins 

Do water drops remind you of small balloons filled 
with water? Get a round balloon and put a little bit of 
water in it. Hold the opening closed and see what shape 
the balloon has when it rests on a table. Fill it with more 
water from the faucet and set it down again to check its 
shape. Keep on forcing water into the balloon until it gets 
quite big. (The safest place to do this is in the bathtub.) 
Now what shape is the balloon? Does a large water bal- 
loon look like a large water drop on the aluminum foil? 

A water drop seems to have a rubber-like skin on it 
too. But the skin of the drop is made only of water. This 
elastic coating of water is caused by something called sur- 
face tension. The stretchy skin of a water drop is so strong 
it can hold up a pin. Lay a pin across a drop on your 

(Continued on the next page) 

13 



What's in a Drop? (continued) 

aluminum foil to sec if it holds the pin up. 

Water in a glass also has an elastic skin. If you care- 
fully lower a needle into some water, you might be able 
to float the needle on this strange skin. Have you ever 
seen insects walking on the water in a quiet stream or 
lake? Now you probably know why they can walk on top 
of the water. (See page 15.) 

You can watch a water drop as it falls and see what 
happens to it. When water drops fall through oil, they 
fall more slowly, so you can watch them all the way down. 
Fill a small jar with cooking oil. Now put a drop of water 
on the oil with a medicine dropper or a paper straw. The 
drop will probably float on top. Do you think this means 
that oil is denser than water? (Did you compare the den- 
sities of oil and water as suggested in "How Dense Are 
You?", N&S, September 30, 1968?) S 

Push the drop down into the oil with your fingers. Now 
what do you think? What held the water drop up on top 
of the oil? Has oil an elastic skin too? If it does, is its skin 
tougher than the skin of water? 

Watch a drop as it falls to the bottom of the oil. What 
shape is it? Try to make a larger water drop. Keep drop- 
ping water on top of the oil until the drop gets so big 



that it falls by itself. Make some drops go down through 
the oil to see what happens when they hit the bottom. 

Drops of Air and Solid Drops 

Have you ever seen air drops? Of course you have; 
that's what bubbles are. You can watch air bubbles in a 
jar of thick liquid like cooking oil or Karo syrup. Shake 
the bottle hard to mix the air with the syrup. What shape 
are the bubbles? Which ones rise faster, the big ones or 
the small ones? Can you think why this might be? 

If water drops freeze, they become solid balls. This is 
how sleet is formed. If you drip melted sealing wax into 
some water it will harden into round little balls. BBs 
(shot) are made by dropping melted lead through a screen 
into a tank of water. When the drops of lead hit the water 
they get hard. 

What is the biggest hardened drop you have seen? 
There is one which everyone knows about. Some scien- 
tists think that in the beginning this drop was just a huge 
piece of hot liquid rock. As it floated through space it 
took the shape of a giant drop. As the drop cooled it be- 
came solid on the outside. If you haven't already guessed, 
this big drop is the earth ■ 



KHOTW1KI 



MEASURING THE SIZE OF DROPS 



The elastic skin of water causes drops to form. Do 
all liquids have an elastic skin like water? Other 
liquids do form drops, so they probably have an 
elastic skin too. But is the strength of the skin al- 
ways the same? You can find out by measuring the 
drop size of different liquids. 

Gather three or four liquids that you want to test. 
You could try some of these: water, milk, cream, 
liquid detergent, salty water, rubbing alcohol, soapy 
water, kerosene, vinegar, cooking oil. 

With an eyedropper, make drops with one of your 
liquids. Notice how the drops form. Are all the drops 
of this liquid the same size? Now make drops with 
some of the other liquids. Do all liquids seem to 
have the same-sized drops? 



y 



y 







One drop is so small that it is hard to measure 
alone. But by putting many drops together, you 
should have enough liquid to measure. Squeeze out 



several hundred drops of one liquid into a small, 
narrow bottle like a pill bottle. Before emptying it, 
mark how high the liquid is. You can stick a piece of 
tape to the side of the bottle and mark the level of 
the liquid with a pencil. You can then count out the 
same number of drops with the second liquid. How 
high up did this one come? Are these drops larger 
or smaller than the first drops? 

Measure the drop size of all the liquids you have 
in this way. You will be able to keep a record of your 
investigation if you fill in the chart. 





NAME OF LIQUID 


LARGEST DROP 




2ND LARGEST 




3RD LARGEST 




4TH LARGEST 




5TH LARGEST 




SMALLEST 





Do you think the liquids with the biggest drops 
have the strongest skins? 



Attacked from the rear by a water strider, which 
walks on the surface of a pond, a slowly 
paddling Stenus beetle suddenly skims forward, 
leaving the strider foundering in its wake. 
Scientists discovered how Stenus does it by— 




by Anthony Joseph 

■ The little beetle called Stenus lives near a pond or a 
stream, where it can often be seen paddling slowly at the 
surface of the water. Every now and then, this beetle 
skims across the water like a jet-propelled surfboard. 
Scientists have long known how Stenus achieves this skim- 
ming motion, but only recently did they find out how it 
helps the beetle escape from one of its predators. 

The discovery was made almost accidentally by two 
biologists, Karl Linsenmair and Dr. Rudolf Jander, of the 
Zoological Institute in Frieburg, Germany. They were 
trying to find out how Stenus turns in different directions 
as it swims or skims along. The more they watched this 
little insect, the more they were struck by the way it could 
change in an instant from a slow, paddling motion to a 
rapid, speedboat-like motion. Sometimes it skimmed as 
fast as 2 l A feet per second, and as far as 45 feet. 

Sinking the Enemy 

The scientists noticed that this happened whenever a 
Stenus was attacked from the rear by a water strider— an 
insect that walks around on the surface "skin" of the water 
(see "What Makes a Drop," page 13). A Stenus would 
sense a water strider sneaking up on it from the rear. In 
a flash the Stenus would skim away, leaving the strider 
foundering in its wake. By observing the Stenus closely, 
the scientists found that it escapes attack from the rear by 
making a fast-moving wave and "surfing" to safety on its 
crest. 

October 14, 1968 



Rinse a dish thoroughly, then fill it with water. Lay a 
needle on a small piece of tissue paper and put it on 
the surface of the water. Can you "float" the needle 
on the water this way? Can you guess why? Now re- 
move the needle and sprinkle some talcum powder 
over the surface of the water. Touch the water at the 
center of the dish with a sliver of soap. Can you ex- 
plain what happens? Will the surface of the water in 
the center support the needle now? 



The Stenus beetle has two tube-like glands near its back 
legs. From these tubes, it squirts a soap-like liquid when- 
ever it is attacked. The liquid weakens the surface tension 
of the water at that point, and the "skin" of the water pulls 
apart in all directions— like the skin of a balloon when air 
breaks through a weak spot in the rubber. The edge of the 
rapidly widening "hole" in the water's skin acts like a 
swift wave that carries the beetle forward. When the "hole" 
reaches the water strider, the insect sinks. 

The scientists found that the Stenus usually escapes in a 
series of short spurts. Going 45 feet at top speed uses up 
all of its soap-like fluid, and it takes a week or so to build 
up a new supply. 

While the water strider has become adapted over mil- 
lions of years so that it can walk on water, the Stenus 
beetle has become adapted so that it can escape from, and 
sink, a strider that attacks it from the rear. The beetle's 
defense is not complete, though— a water strider that at- 
tacks it from the front gets its prey nearly every time* 

15 



WHAT'S 
NEW 

by 

Roger George 





Egg-stealing scientists may be 

helping the whooping crane win its bat- 
tle for survival. The scientists began their 
fight to save the whoopers from extinc- 
tion in 1938, when there were only 14 of 
the giant white birds left in the world. 

The number of birds increased over 
the years, but only very slowly. The prob- 
lem was that few young birds were able 
to survive their first year in the wild. 
That's why scientists started stealing 
eggs. In the last two years they've taken 
a dozen eggs from the nests of whoopers 
in remote northern Canada, hatched 
them at a wildlife research center in 
Maryland, and raised the young birds in 
captivity (see photo). Almost all have 
survived. As a result, the total population 
of whooping cranes is now nearly 70. 

Red, orange, and yellow mud 

fell on England recently. It all began with 
dust from the Sahara Desert, over 1,000 
miles away. Strong winds had lifted dust 
from the African desert high into the air 
and carried it over England. There the 
dust mixed with rain and fell as mud. 
Once before, in 1902, dust clouds were 
blown from Africa to England. 

Other severe dust storms are on rec- 
ord. In 1912, for example, dust from the 
eruption of an Alaskan volcano settled 
on Seattle, Washington, 1,600 miles 
away. During the 1930s, disastrous dust 
storms over the southwestern United 
States picked up fertile topsoil and de- 
posited it as far away as the Atlantic 
Coast, leaving behind the barren dust 
bowl of the Great Plains. 

Objects falling from space arc a 

threat to high-flying aircraft. In the past 
five years, airline crews have reported 
seeing at least 1,230 falling objects. Of 
these, 1 ,077 were classified as meteors. 
loo were man-made satellites and other 
known objects, and 23 were pieces of 
unknown debris. Thirty were classified as 
UFOs (unidentified flying objects). 

16 



Pilots are now being warned when 
spacecraft debris will re-enter the atmo- 
sphere. But today's jets, which travel at 
altitudes of about 35,000 feet, are not 
likely to be damaged by falling objects. 
Before most objects fall to this altitude, 
they are burned up through friction with 
the air. Others are broken up and slowed 
down. Supersonic jets of the future, how- 
ever, will fly at about 70,000 feet. At this 
altitude there is more debris, and it is 
falling at the rate of 2,000 miles an hour. 
So even a tiny piece could cause serious 
damage. 

"It's too quiet," grumbled em- 
ployees in a new $10 million office build- 
ing in Cologne, Germany. The modern 
soundproofing system worked so well 
that workers couldn't stand the silence. 
Engineers are now planning to record 
background sounds of traffic, telephones, 
and typewriters, and pipe them through- 
out the building. 

Apparently silence is not golden when 
there is too much of it. The ideal sound 
level seems to lie somewhere between 
a whisper and a roar. 

There may be life on Venus, Mars, 
and Jupiter. At least, recent U.S. and 
Soviet space probes suggest this possibil- 
ity. Oxygen has been detected on Venus, 
for example. The oxygen could be the 
product of living plants, says Dr. Willard 
F. Libby, a chemistry professor at the 
University of California. Most of Venus 
is too hot for plants, but there seem to 



be huge ice caps at its poles. Plants might 
be able to grow near the ice. 

Unlike Venus, Mars is frigid. But 
some simple forms of life can survive in 
extreme cold. Besides, Mars probably 
once had a milder climate. Living things 
could have developed in the milder cli- 
mate, and then adapted to the slowly 
cooling conditions, says Cyril Ponnam- 
peruma, a chemist for the National Aero- 
nautics and Space Administration 
(NASA). 

As for Jupiter, life may be develop- 
ing there right now, according to Harold 
P. Klein, another NASA scientist. Con- 
ditions on Jupiter may be something like 
those on the earth billions of years ago, 
at the dawn of life. 

Is the steam car the dream car 

of the future? Some scientists think so. 
They say that steam-driven cars won't 
pollute the air nearly as much as gaso- 
line-powered cars. A steam engine burns 
fuel much more completely than a gaso- 
line engine does, so far fewer particles 
and fumes are left to escape into the air. 
The steam car should also be cheaper to 
buy and maintain than a gasoline-engine 
car. And it is expected to travel up to 100 
miles an hour and average about 30 miles 
per gallon on inexpensive fuel. 

Why, then, aren't steam cars in the 
showrooms? One reason is that setting up 
production lines will take a lot of money. 
Perhaps the government may have to 
help out if steam cars are to be mass- 
produced. 




The baby whooping crane, shown standing in its dish of drinking water, was hatched 
recently at a wildlife research center in Maryland. When it is grown, it will look like 
the adult whooping cranes at right, on display at The American Museum of Natural 
History in New York City. 



NATURE AND 5CIEM I 



Using This Issue . . . 

(continued from page 2T) 

dispersal among animals is generally 
active, while in plants it is most often 
passive. That is, it is usually effected 
, by external agents such as wind, water, 
animals, and man. Exceptions are those 
plants that actually shoot their seeds 
from pods (the range of spread in these 
cases, however, is never very great). 
The great seed-spreaders are birds and 
man. 

Topics for Class Discussion 

• Have your pupils consider the 
many seeds produced by a single plant. 
Do they see a relationship between the 
number of young that a species of liv- 
ing thing produces and the chances 
that the species will survive? Mice and 
rabbits are good examples of animals 
that produce many young and have a 
high rate of mortality. 

• Of the seeds that are spread by 
man, what kinds are apt to be carried 
on purpose and what kinds by acci- 
dent? Food plants are spread delib- 
erately,weeds accidentally. The Russian 
thistle entered this country in a bag of 
flax seed and quickly became a pest to 
farmers. Many other common weeds in 
the United States were brought acci- 
dentally from Europe. 

• Will seeds collected in the fall 
sprout if planted indoors? Some will, 
but many seeds need a period of cold 
temperatures (such as they would be 
exposed to outdoors) before they will 
sprout. Florists often keep seeds re- 
frigerated for a time to simulate cold 
winter temperatures. 

Activities 

• Fall is an excellent time to gather 
seeds. Let the class arrive at a way of 
sorting and arranging them for display. 
Very likely they will choose to organize 
seeds by the way they travel. Seeds may 
be glued onto construction paper, or 
dried (to prevent mold ) and displayed 
in clear plastic envelopes. 

Keep mystery seeds to one side and 
encourage identification by letting the 
pupil who solves the mystery add the 
seed in question to the regular display. 

• Someone might read and report 
on John Chapman, better known as 
"Johnny Appleseed." 

October 14, 1968 



What Makes a Drop? 

• After completing the suggested 
investigations, your pupils might— with 
a little help— be able to guess what 
causes the surface of a liquid to act 
like an elastic skin (the surface tension 
effect). Remind them of the forces of 
cohesion and adhesion mentioned at 
the end of "Climbing Water" (N&S, 
Sept. 16, 1968), and ask if they think 
water attracts water more strongly than 
it attracts air. It does (see diagram 
below). 




^^$^^$$$$$$$$$$$$$$$$ 



The molecules, or smallest particles, of 
water at the surface of a drop are attracted 
to the water within the drop more strongly 
than to the gas molecules in the adjoining 
air. This makes the surface water mole- 
cules act like a "skin." 

• A swimming Stenus beetle (see 
page 15) is pulled in all directions with 
equal force by this elastic skin at the 
surface of the water (Diagram A). 




When the beetle secretes a soap-like 
liquid from the rear, the surface ten- 
sion there is weakened, allowing the 
beetle to be pulled forward (Diagram 
B). 

• How do soap and other detergent 
chemicals help us wash greasy dishes 
and dirty clothes? They weaken the 
"skin" of water, allowing it to mix 



more freely with the dirt and grease 
so they can be rinsed away. 

Brain-Boosters 

Mystery Photo. The photo shows a 

small waterfall, only a few inches high. 

What would happen if? Cut a wedge 
from a paper plate and let your pupils 
observe the motion of the rolling mar- 
ble. If the table is level, the marble will 
leave the plate in path C, a straight line 
tangent to the marble's previous circu- 
lar path. 

The motion of the marble is ex- 
plained by Newton's law of inertia: An 
object in motion will tend to keep mov- 
ing in a straight line at constant speed 
unless acted upon by an outside force. 
The marble's motion around the plate 
actually consists of an infinite num- 
ber of tiny, straight-line motions in 
directions tangent to the marble's cir- 
cular "track." The rim of the plate 
provides the outside force that keeps 
changing the marble's direction, forc- 
ing it into a circular path. When the 
marble reaches the break in the plate, 
there is no longer any force acting on 
it to change its direction, so it contin- 
ues to move in the straight line it was 
following at the instant that it left the 
plate. Frictional force between the 
marble and the tabletop slows the mar- 
ble down, however. 

If the tabletop were slanted, then 
another force, gravity, would act on 
the marble, causing it to curve in its 
path. 

Can you do it? It is possible, though 
inconvenient, to swallow while you are 
upside down. Muscles of the esophagus 
contract in sequence to force the water 
(or food) toward the stomach, whether 
you are in a normal or inverted posi- 
tion. This action, known as peristalsis, 
can be easily seen when a person is 
swallowing. 

Ask the class whether they think 
that all animals have muscles that force 
food to their stomach. Perhaps some- 
one will have noticed that birds (which 
lack such muscles) drink by first dip- 
ping their beak into the water, then 
throwing their head back. This action 
enables gravity to make the water (or 
food) fall into their stomach. 

Fun with numbers and shapes. The 
(Continued on page 4T) 

3T 



Using This Issue . . . 

(continued from page 3T) 

minute hand of a clock passes the 
hour hand only 1 1 times in 12 hours. 
If the children have difficulty visualiz- 
ing this, let them turn the hands on a 
clock or on their own wristwatches 
through 1 2 hours and see. 

For science experts only. If you can 
afford the probable loss of a yardstick 
(or can get a similar stick from a wood- 
working class), you can use it to dem- 
onstrate dramatically that the earth's 
atmosphere exerts a pressure. (We are 
not usually aware of air pressure, be- 
cause—except when the wind is blow- 
ing—the pressure is the same on all ex- 
posed parts of the body.) 

When you strike the free end of the 
yardstick, the covered end begins to 
move up, carrying the sheet of news- 
paper with it, and causing a partial and 
momentary vacuum beneath the paper. 
Normal atmospheric pressure against 
the paper will hold the paper and yard- 
stick down long enough for the stick 
to break, if it was hit hard enough. 

Just for fun. After your pupils try 
this, you might ask them why cold 
water is denser than hot water. (The 
concept of density is explained in 
"How Dense Are You?", N&S, Sept. 
30, 1968, pages 10 and 2T.) When 
water or any other substance is heated, 
the tiny particles of matter that make 
up the substance (molecules) move 
around faster than before and bounce 
farther apart when they collide with 
each other. The substance therefore 
expands, or fills a larger volume of 
space, and so becomes less dense than 
before. 

As the colder, denser water sinks 
through the warm water, it is warmed 
up a bit, and is pushed upward by the 
colder water sinking from the ice cube. 
This produces a flow of water (and 
pepper) down and up in the glass. Such 
a flow is called a convection current, 
and it occurs whenever two masses of 
fluid (liquid or gas) at different tem- 
peratures come together. Can your 
pupils think of some examples of con- 
vection currents in nature? Ocean cur- 
rents and the winds (convection cur- 
rents in the atmosphere) arc two such 
examples. 



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4T 



nature and science 

TEACHER'S EDITION 

VOL. 6 NO. 4 / OCTOBER 28, 1968 / SECTION 1 OF TWO SECTIONS 

COPYRIGHT © 1968 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 



USING THIS ISSUE OF NATURE AND SCIENCE 
IN YOUR CLASSROOM 



Has earth science always seemed a 
rather static and dull subject to your 
pupils— and perhaps to you? 

This special-topic issue should 
change your opinions, for it presents 
a fascinating, up-to-the-minute picture 
of scientists working in ingenious— and 
sometimes dangerous— ways to investi- 
gate the mysterious forces that are con- 

j stantly changing the unstable "plat- 

' form" we live on. 

Faults of Earthquakes 

• A fault in the earth, where earth- 
quakes begin, is something like a break 

; in the pavement or sidewalk where the 
concrete block on one side of the break 

j has been pushed down or sideways past 
the block on the other side, perhaps by 
a heavy truck. Like such a break, a 
fault may disappear at each end, where 
the material on each side joins 
together, or the fault may join other 
faults at one or both ends. 

If the block on one side of a "side- 
walk fault" is loosely supported, or is 
free to move along the ground, a per- 
son stepping on it may get shaken up 
as the block drops, rocks, or slides 
under him. This is what happens to the 
earth when a rock mass inside it sud- 
denly moves along a fault. 

• The idea of a rock mass "bend- 
ing" may be hard for your pupils to 
believe. Point out that heat and great 
pressure within the earth make the 
rock there more "elastic" than surface 
rock. 

Activity. Here is a way to show your 
pupils how a rock mass that has been 



kept from moving along a fault stores 
up enough energy to overcome the fric- 
tion that held it back, and releases this 
energy in a sudden movement that 
causes an earthquake: 

Place some old dishes on a heavy 
table or chest (the "rock mass" on one 
side of a fault). Have a pupil try to 
push the table along the floor (the 
"rock mass" on the other side of the 
fault) . If the table slides over the floor 
easily, it may move without shaking 
the dishes (which represent the surface 
of the earth) . But if it has to be pushed 
awhile to get it moving at all, the table 
stores up the pushing as potential 
energy— until it has enough energy to 
overcome the friction with the floor. 
Then the table springs forward sud- 
denly, shaking the dishes on top. (A 
molded gelatin dessert on one of the 
dishes will heighten the effect. ) If the 
table slides easily, you might block it 
from the other end, then release it sud- 
denly as the child is pushing. 

• To help your pupils understand 
how the Rouse belts were discovered, 
have them compare the diagram at the 
top of page 4 with the sliced-open 
globe in the center background of the 
photo on page 3. The diagram shows 
how deep faults in a particular earth- 
quake zone are arranged in a "flat" 
pattern, or plane. When this plane is 
projected ("stretched out") in all 
directions, it meets the surface of the 
earth at an angle of about 60° along a 
large circle on the globe. 

Activity. You can make a card- 
board "plane" like the one shown on 
(Continued on page 2T) 




IN THIS ISSUE 

(For classroom use of articles pre- 
ceded by%, see pages IT, 2T, 3T.) 

• The Faults of Earthquakes 

Your pupils will find out how an 
earthquake starts at a "break" in the 
earth, and how a graduate student 
discovered a new way to investigate 
these mysterious breaks. 

• Inside the Earth 

Earthquake waves tell scientists 
where a quake occurs and what the 
inside of the earth may be like. 

Earthquake Lab 

How scientists at a new research 
center in California study large and 
small earthquakes. 

• Shaping the Earth's Crust 

This Wall Chart shows some of 
the ways that mountains, plateaus, 
and valleys are formed by forces 
working inside the earth. 

Kilauea Blows Its Cool 

Scientists braved fiery lava foun- 
tains to study this volcanic eruption 
— a fascinating Science Adven - 

TURE 

• World's Biggest Jigsaw Puzzle 

The mystery of whether the conti- 
nents were once joined together may 
be nearing a solution. 

• Brain-Boosters 



IN THE NEXT ISSUE 

How a zoo doctor keeps thousands 
of exotic animals healthy . . . Explor- 
ing the structure of wood ... A Wall 
Chart showing how scientists find 
the ages of animals . . .The birth and 
use of the barometer . . . Making the 
most of yeast. 



Using This Issue . . . 

(continued from page IT) 

page 3 that will meet the surface of 
your classroom globe at a 60° angle. 
Multiply the diameter of your globe by 
0.87 to find the diameter for the hole 
in the cardboard (10 7/ 1(; inches for a 
1 2-inch globe) . Use a compass to draw 
the circle, and scissors or a knife to 
cut the circular hole. If your globe has 
a vertical support reaching to the 
"North Pole," cut a slit in the card- 
board so it can be slipped over the sup- 
port to fit over the globe. 

Have your pupils fit the plane over 
the top of the globe so that the edge of 
the hole lines up with Mexico City 
(where an earthquake killed three 
persons on August 2, 1968) and 
with Costa Rica, in Central America 
(where a volcano— Mt. Arenal— erup- 
ted July 29, 1968). If the plane was 
fitted properly, your pupils will find 
that the circle it makes with the surface 
of the globe also runs through Iran, in 
the Middle East, where some 12,000 
people died in an earthquake on Au- 
gust 31, 1968. 

Inside the Earth 

• Your pupils may wonder why a 
weighted pen hanging by a wire from 
the frame of a seismograph doesn't 
vibrate when an earthquake wave 
shakes the frame and recording drum. 
Too little of the wave's energy is trans- 
mitted through the wire to overcome 
the weighted pen's inertia, or tendency 
to remain at rest. (Inertia is what 



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makes a bicycle rider use more energy 
to start the bike from a dead stop than 
he uses to keep it moving once it is 
started.) 

• Seismologists use a table based 
on the travel speeds of P-waves and 
S-waves along different paths through 
the earth to find the distance of a 
quake's epicenter from the seismo- 
graph. For example, if the first S-wave 
arrives 2 minutes and 41 seconds after 
the first P-wave, they can tell from the 
table that the epicenter is 1,000 miles 
away from the seismograph. The dia- 
gram shows how the distances of the 




The circle drawn on a map around each of 
these seismograph stations has a radius 
equal to the distance the earthquake 
waves traveled to reach the station, so 
the epicenter of the earthquake must lie 
where the circles intersect. Can your pu- 
pils guess why the distances from at /east 
three widely separated stations must be 
known to locate an earthquake? 



epicenter from three (or more) widely 
separated stations are used to locate it. 
Activity. Have your pupils make 
compression waves (P-waves) and 
shear waves (S-waves) as shown at 
the right to help them understand why 
P-waves can travel through a solid, 
liquid, or gas, while S-waves can only 
travel through a solid material, whose 
particles (molecules) keep their ar- 
rangement when the material is shaken 
up and down or sideways. 

Shaping the Earth's Crust 

Since this issue concentrates on 
changes caused by forces working 
within the earth, the role of erosion in 
shaping the earth's crust is not dis- 
cussed in detail in this Wall Chart. 
For further references on erosion, see 



"Is the 'Great Ice Age' Over?", N&S, 
Sept. 16, 1968; "Grandest of All Can- 
yons," N&S, Nov. 13, 1967; and 
"How Ice Changed the Land," N&S, 
Dec. 19. 1966. 

Biggest Jigsaw Puzzle 

The theory of continental drift— that 
the continents were once joined in a 
single land mass but have split off and 
"drifted" apart during the past several 
hundred million years— is not yet com- 
pletely accepted by all scientists. How- 
ever, more and more evidence that 
seems to support the theory is being 
discovered. This fascinating new 
article by Mrs. Sherman (who wrote 
an article with the same title in N&S, 
March 7, 1966) brings the subject up 
to date, including news about an 
ocean-drilling project now in progress 
that may turn up evidence that could 
solve this mystery. 

Activity. To help your pupils under- 
stand what happens when the earth's 
magnetic field reverses polarity (see 
page 15), hold a toy compass over a 
bar magnet and turn the compass until 
the "north-seeking" end of its needle 
(usually colored) points to "N" on the 
compass face. Then turn the bar mag- 
net in the opposite direction so they 
can see the needle's north-seeking end 
pointing to "S" on the compass face. 
Explain, though, that the "magnet" in 
the earth does not turn around like the 
bar magnet; instead, the earth's mag- 
netic field seems to get weaker and 
(Continued on page 3T) 



•®@©®-® 



When penny A strikes penny B, the "push" 
is passed along through C and D to E in 
a compression wave whose energy moves 
E just as P-waves from a suddenly moving 
rock mass in the earth move the surface 
of the earth above the rock mass. 





Shaking one end of a rope up and down 
sends shear waves through it, moving the 
loose end just as S-waves from a suddenly 
moving rock mass in the earth move the 
surface above it. Can you send S-waves 
through a line of pennies? 



2T 



NATURE AND SCIENCE 



VOL. 6 NO. 4 / OCTOBER 28, 1968 



srtuiAL- luriu ibbut 



WHAT'S HAPPENING 



IN THE EARTH'S CRUST 




nature and science 

VOL. 6 NO. 4 / OCTOBER 28, 1968 



CONTENTS 

2 The Faults of Earthquakes 

4 Man-Made Earthquakes?, by Esther S. Wilson 

5 Inside the Earth 

6 Earthquake Lab, by Ruth and Louis Kirk 

8 Shaping the Earth's Crust, 

by Margaret E. Bailey 

1 Kilauea Blows Its Cool 

12 The World's Biggest Jigsaw Puzzle, 

by Diane Sherman 

16 Brain-Boosters, by David Webster 

This issue was prepared with the advice and assistance of Chris- 
topher J. Schuberth, Senior Instructor in Adult Education at The 
American Museum of Natural History. 

PICTURE CREDITS: Cover, p. 12 by Robert Goodman, from Black Star; 
p. 3, Office of Public Information, The Colorado School Of Mines; pp. 4, 5, 7, 
10, 11, 13, 14, 16, drawings by Graphic Arts Department, The American 
Museum of Natural History; pp. 6-7, photos by Ruth and Louis Kirk; p. 8, 
top photo from Utah Travel Council (Parker Hamilton), bottom photo from 
Union Pacific Railroad; p. 9, top left and bottom left photos from AMNH, 
top right photo from Japan National Tourist Organization, bottom right photo 
by Christopher J. Schuberth; p. 9, drawings by Gail Winbigler; p. 15, drawings 
by Ren6 Moens; p. 16, upper left photo by David Webster, lower left photo by 
Joan Hamblin, right photo by Franklyn K. Lauden. 



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What causes the breaks in the 
earth where earthquakes begin? 
A graduate student with a toy 
globe has discovered a new 
way to investigate— 



faults o/ 



Earthq 



u; 



■ Most seismologists, or scientists who study earthquakes, 
agree that earthquakes usually begin when a rock mass 
beneath the earth's .surface moves suddenly. This some- 
times happens when the hot gases and molten rock that 
feed a volcano push the surrounding rock hard enough to 
move it. Or it may happen when loosely packed rocks near 
the surface of the earth shift under the pressure of the rock 
layers above them (see "Man-Made Earthquakes?", page 



This shifting, shaking, rising, falling, 
erupting, folding, cracking 
platform we live on 

The earth's surface is never at rest. It is con- 
stantly being shaken by earthquakes; pushed up 
or covered over by molten rock from inside the 
earth; pushed up, pulled down, folded or 
broken by forces that we do not yet fully under- 
stand; and worn down by the force of erosion, 
which we do understand. The continents may 
even have been split apart from one "super- 
continent" and moved to where they are now. 
We don't know what causes these immense 
changes in the earth. The answers seem to be 
buried within the earth, and neither instruments 
nor men can go down very deep to investigate 
them. But without leaving the surface of the 
earth, scientists are finding out more and more 
about what goes on inside it. This special-topic 
issue tells you some of the ways they do this 
and what they are finding out about the forces 
that make our platform so unstable. 



. 




George Rouse (left) and Dr. Ramon 
Bisque draw circles on a globe where the 
planes of deep earthquake zones would 
meet the surface if they were "stretched 
out." The hoop is the same diameter as 
the hole in the cardboard "plane" (above) 
Rouse first used to find these "belts." 
The belts run through the sites of most 
of the world's earthquakes, volcanoes, 
and mountain ranges. 



. But such quakes seldom shake a very large area of the 
xth's surface. 

The sudden rock movements that cause most earth- 
lakes seem to happen at places in the earth called fault 
nes. A fault is a break in the earth where the rock mass 
i one side of the break has moved past the rock mass on 
e other side. The break itself, called the fault plane, may 
tend for miles. Most faults lie from 2 to 20 miles under 
e earth's surface. Some, however, reach up to the sur- 
ce, where the shifting of one rock mass past the other 
n be seen and measured (see "Earthquake Lab," page 6). 
ther faults are as deep as 400 miles, within the earth's 
)per mantle (see "Inside the Earth," page 5). 
The trouble seems to start when a gradually shifting 
ck mass is stopped, or slowed down— perhaps by rocks 
the two masses getting stuck together along the fault, 
le push or pull that moved the rock mass before now 
nds it like a bow. When there is enough strain to pull 
z sticking rocks apart, the rock masses on either side of 
3 fault snap past each other, sending waves of vibrations 
rough the earth and shaking hundreds of square miles of 
; surface. 

This may explain how most earthquakes happen. But 
:e most scientific explanations, it raises further questions: 
hy are there faults in the earth? And what makes rock 
asses move along these faults? 

vestigating with a Toy Globe 

Questions like these bothered Dr. George Rouse when 
was working for his doctor's degree in earth chemistry 

October 28, 1968 



last year at the Colorado School of Mines, in Golden. 
While studying for an exam, he came across a fact that 
puzzled him. An American seismologist named Hugo 
Benioff had discovered that the deeper faults in the mantle 
are arranged in flat "zones," or planes, and that these 
zones are slanted at an angle of about 60 degrees to the 
earth's surface. Rouse wondered why this should be. 

He bought a toy globe for $1.50 and tried out an idea. 
He wanted to see what would happen if one of the deep- 
fault zones were "stretched out" far enough to reach the 
earth's surface on all sides. To find out, he cut a round 
hole in a piece of flat cardboard so that it would fit over 
the globe at a 60° angle to the surface of the globe (see 
photo). 

Rouse first lined up the cardboard "plane" with the 
plane of an earthquake zone that lies deep in the earth off 
the coast of Chile. Along the circle where the plane met 
the globe, he found other places where there is a lot of 
earthquake activity— in the Pyrenees Mountains of France, 
in the Red Sea, and at the tip of South America. 

He marked that circle on the globe. Then he lined up 
his cardboard plane with the planes of other deep-fault 
zones and drew circles where they would meet the surface 
of the earth if they were stretched out. In all, he drew 1 6 
circles, or "belts" on the globe's surface (see photo). 

To his amazement, Rouse found that these belts passed 
through all of the places where earthquakes occur most 
frequently. In fact, there were 1 9 places on the globe where 
three belts crossed each other, and most of these were 

(Continued on the next page) 



A million earthquakes a year! Scientists believe that 
many are strong enough to make you feel the earth 
shake if you were at the right place at the right time. 
Many, many more are too weak for you to feel, but 
they are detected by se/smographs (see page 5). 

Very few earthquakes cause much damage, either 
because they are too weak or because there is nothing 
much to damage where they occur. But each year 
several strong quakes shake the surface in areas 
where people live. Such quakes result in the deaths 
of thousands of people and damage millions of dol- 
lars worth of buildings and property each year. 

The Faults of Earthquakes (continued) 
places where there is strong volcanic and earthquake ac- 
tivity (see map on page 15). 

Clues to the Cause of Faults? 

Rouse and Dr. Ramon Bisque, a Professor of Geo- 
chemistry at the Colorado school, discovered that impor- 
tant deposits of minerals, large mountain systems, 
ocean-floor ridges and trenches, and volcanic island chains 
lie along what are now called the "Rouse belts." So do a 
number of places where the earth's magnetism and the 
force of the earth's gravity seem to change in strength. 

Rouse also found that if the deep-fault zones were 
"stretched," they would all pass along the boundary be- 



CORE 



MANTLE 



ZONE 
'STRETCHED OUr- 



■DEEP-FAULT ZONE 

tween the earth's mande and 
its outer core (see diagram; 
also page 5). The scientists 
pointed out that there is 
some evidence that the mag- 
netism of stars and other 
planets creates a field of 
magnetic force throughout 
space. Rouse and Dr. Bisque 

think this magnetic field may pull on the earth's iron core 
in a way that would make it turn differently from the rest 
of the earth if the mantle did not hold the core in line. 
This kind of "tug-of-war" between the core and the mantle 
would probably cause stresses and strains at the boundary 
where they meet. 

These strains, the scientists suggest, are then passed 
upward through the mantle along the planes where the 
deep faults are found. If this is so, these strains could be 
the cause of the faults in the earth's upper mantle and 
crust, and they could cause the movements of rock masses 
along those faults. 

Whatever the explanation, Rouse's discovery seems to 
show that earthquake zones nearly halfway around the 
globe from each other are somehow connected. This raises 
many questions, and it opens a new path for scientists who 
investigate the forces that shape— and shake— the earth ■ 



Man-Made 
Earthquakes? 



.:'.-. 



The area around Denver, Colorado, hadn't been shaken by an 
earthquake for 80 years until April 1962. Since then, Denver 
has had more than 700 earthquakes — as many as 44 in one 
month. None of them caused much damage, but there was 
always the chance that they might get more severe. 

In November 1967, a possible cause for these quakes was 
suggested by David M. Evans, a consulting geologist at the 
Colorado School of Mines, in Golden. He had discovered that 
the quakes all began within five miles of a 12,000-foot well 
that had been drilled into the rock at the United States Army's 
Rocky Mountain Arsenal near Denver. The Army began 
pouring poisonous waste water from the arsenal into the well 
in March 1 962, and the quakes began in April. 

Evans showed that the number of earthquakes per month 
seemed to rise or fall according to the amount of water that 
had been pumped into the well each month. The quakes con- 
tinued, though, even after the Army stopped pouring wastes 
into the well in early 1966. In fact, the three strongest quakes 
were in 1967. 




Remove one end from an empty pop can, and punch 
about a dozen holes through the other end. Place the 
can, punched end down, on a smooth board, and lift 
one end of the board until the can almost— but not 
quite— slides. Put a block under the board to hold it 
at that angle (see diagram). Move the can to the high 
end of the board and pour water into it. What happens 
as the water piles up in the can? 



Evans used this demonstration to show that the water had 
probably seeped into faults in the rock layers around the bot- 
tom of the well and made it easy for the rocks to slide over 
each other. Like the water in the can, the water in the well is 
still pushing out through the faults in the surrounding rock. 

As this is written, the Army is trying to pump the water back 
out of the well — but just a little bit at a time. They hope this 
will keep the rocks from slipping suddenly as the removal of 
water lowers the pressure in the well. — Esther S. Wilson 



NATURE AND SCIENCE 



■ Have you ever wondered how scien- 
tists can tell that an earthquake has 
occurred thousands of miles away in a 
place where no one lives? The message 
is delivered by the waves of vibrations 
that spread out in all directions through 
the earth when an earthquake occurs. 
At more than 500 stations around the 
globe, these waves are measured and 
recorded by instruments called seis- 
mographs (see diagram). 




Anchored in bedrock, this simple seis- 
mograph records earthquake waves that 
shake the frame and rotating drum, but 
not the weighted pen hanging on a wire. 
Electronic seismographs used by scien- 
tists (see next page) work much the 
same way. 

The first kind of wave that reaches 
a seismograph from an earthquake is 
the push, or compression wave. You 
can feel a compression wave if you 
press your finger against one end of a 
metal rod and strike the other end with 
a hammer ( see diagram). 

The second kind of wave that 
reaches a seismograph is the shake, or 
shear wave. To feel shear waves, press 
your finger to the side of a metal bar 
and strike the side of the bar with a 
hammer (see diagram). 




COMPRESSION WAVES 




It A t A t A t A t 

SHEAR WAVES 





Compression waves travel faster 
than shear waves through the same 
kind of material. Because the compres- 
sion waves from an earthquake reach a 
distant seismograph first, they are 
usually called primary, or P-waves; 
shear waves are called secondary, or 
S-waves. (When P- and S-waves reach 
the surface of the earth, they set up the 
surface waves that shake the ground 
and cause damage. ) 

S-waves travel only about two-thirds 
as fast as P-waves through material of 
the same density (see "How Dense Are 
You?", N&S, September 30, 1968). So 
by measuring the time between the ar- 
rival of the first P-wave and the arrival 
of the first S-wave at a seismograph 
station, scientists can figure out the dis- 
tance from the earthquake to the sta- 
tion. With this information from at 
least three widely separated stations, 
they can locate the earthquake's epi- 
center — the place on the surface di- 
rectly above the shifting rock mass that 
started the earthquake underground. 

But that's not all. Earthquake waves 
have also helped us get some idea of 
what the earth is like inside. 

Seismologists know that the more 



rigid, or "stiff," a material is, the faster 
P- and S-waves move through it. And 
the more dense a material is, the slower 
it carries these waves. As the waves 
move from one kind of material into 
another kind, they are "bent," or re- 
fracted, so they follow curved paths 
through the earth (see diagram). 

These paths show that the density of 
the earth increases with depth. They 
also show that the earth has a crust of 
rock about 20 to 30 miles thick under 
the continents, but only 2 or 3 miles 
thick under the oceans. Beneath the 
crust is the mantle, made of denser 
rock and reaching to a depth of about 
1,800 miles. 

Inside the mantle is the earth's core, 
which scientists believe is made of 
metal — mostly iron. But S-waves, 
which can only pass through solid ma- 
terials, disappear when they reach the 
core. That is why scientists think the 
outer part of the core is a liquid — prob- 
ably molten metal. P-waves pass 
through the core, however. Those that 
pass through the inner part of it are 
speeded up so much that scientists 
think the inner core is made of solid 
metal ■ 



-^ 



ORIGIN OF 
EARTHQUAKE 




The curved paths that P- and 
S-waves follow through the 
earth show that the earth's 
density increases with depth. 
S-waves can only travel 
through solid material, and 
they disappear at the outer 
core, which scientists believe 
must be a dense liquid — 
molten metal. The paths of 
P-waves that pass through 
the inner core show that it 
must be solid metal. 



CRUST 



David Stuart examines the wiggly line that 
shows how the earth vibrated at a point 60 
miles from the research center over a period of 
nearly 24 hours. A seismograph like this is 
wired to each of 30 seismometers (instruments 
that measure earth shakes) buried along the 
San Andreas fault and other smaller faults 
nearby. Scientists can tell by the sharpness of 
the "wiggles" whether the earth was shaken by, 
say, a truck or falling tree, or by an earthquake 



EARTH 



■ "Nobody can stop earthquakes, but we should learn to 
live with them." This is the purpose of the new National 
Center for Earthquake Research at Menlo Park, Califor- 
nia, according to David Stuart, Assistant Chief of the 
Office of Earthquake Research and Crustal Studies there. 

In 1965 the United States Geological Survey set up this 
station near the San Andreas fault ( see map and photo at 
right and "The Faults of Earthquakes," page 2). The area 
along this fault is called the "earthquake capital" of the 
U.S., because more quakes happen there than anywhere 
else in the nation. 

The photos on these pages show some of the ways that 
geophysicists (scientists who study the earth's structure) 





DUAKE 



investigate quakes along a fault. Another way (not shown) 
is to drive stakes on opposite sides of a fault and keep 
track of how far and how fast they shift past each other 
This shows how much strain, or pressure, is pushing th< 
rock masses in horizontal directions. Sensitive tiltmeter, 
(see "Kilauca Blows Its Cool," page 10) measure th< 
strains that tend to shift the rock masses up or down. 

The main goal of these scientists is not necessarily tc 
predict when an earthquake will happen. "First," sayi 
Stuart, "we need to understand what happens during ai 
earthquake. When we do, we can give advice about th< 
danger of quakes— which really is as urgent as telling wher 
they may happen. We can help architects decide wha 
kinds of buildings will be safest, and where to build them.' 

San Francisco and Los Angeles are already built alons 



In the lab, geophysicist Jim Gibbs places a half- 
inch cylinder of rock into a chamber where it 
will be squeezed and heated like rock deep in 
the earth, where some earthquakes occur. Dr. 
C. Barry Raleigh, another geophysicist, is using 
the chamber to find out why rocks 400 miles or 
so within the earth seem to act like plastic, or 
putty. 



NATURE AND SCIENCE 





by 
Ruth and Louis Kirk 



I 

ine of earthquake hazard, but some places along the line 
s worse than others. Geophysicists hope someday to see 
>mes and schools and offices moved away from the fault 
elf and onto the most stable ground available. As it is 
w, many real estate developers build where scientists 
t.ow there is sure to be trouble some day. 
< "As for foretelling when a quake will come at a certain 
ace," Stuart says, "the most we may someday be able to 
> is about what the weatherman does now. Someday we 
ay be able to say 'There is a 60 per cent chance of an 
rthquake' on a certain day. And when we do, we'll prob- 
ly have as many people mad at us as the weatherman 
5 now!" ■ 



In a field test (left photo), electronic technician Herb 
Mills prepares to string out six seismometers attached 
to iy 2 miles of wire over an area where small quakes 
following a large one are still shaking the earth (or 
where a test explosion will be set off). The vibrations 
detected at different places are recorded on a magnetic 
tape. Playing the tape back at the research center (right 
photo), geophysicist Rex Allen watches the vibrations 
on a TV-like oscilloscope screen. When he sees an earth- 
quake pattern, he records it on paper for further study. 
Since the vibrations pass through different types of 
rock at different speeds, these tests help scientists find 
out what kinds of rock make up the quake zone. 



lis map shows where 
e research center is 
:ated along the San 
idreas fault. The photo 
ows co-author Louis Kirk 
amining a break in the drainage 
tch at a winery near Hollister, 
ilifornia. Part of the ditch has been 
if ted about six inches by the movement 
rock along the fault. This movement 
is been going on for about 100 million 
ars. If the land where San Francisco 
built has been moving at its present 
eed during all that time, it could have 
arted from where Los Angeles is now! 

October 28, 1968 




PACIFIC 

OCEAN 



I 

October 28, 1968 



SH JIPING «» 



■ No one knows exactly when or how 
the earth's crust formed, but we do know 
that the shape of its surface has been 
changing ever since. 

The surface has often been pushed up- 
ward or broken open by molten rock ris- 
ing through cracks in the crust. Where 
this molten rock spills out onto the sur- 
face it builds mountains and plateaus of 
volcanic rock. This kind of activity is 
called vulcanism (see diagrams and 
photos). 

When parts of the surface are 
squeezed together, pushed upward, or 
pulled downward, the rocky crust is 
folded or broken, forming mountains 
and valleys. This kind of activity is 
called diastrophism (see diagrams and 
photos). 

Tiny pieces of rock and soil are con- 
tinually being rubbed off high places on 
the surface and being carried away to 
lower places by moving water and ice. 
As you probably know, this activity is 
called erosion. 

Erosion is caused mostly by the pull 
of the earth's gravity on water and ice. 
But we don't know yet what causes vul- 
canism or diastrophism. One old idea is 
that the earth is cooling off and shrink- 
ing. A newer idea is that vulcanism and 
diastrophism are signs that the earth is 
heating up and expanding. Another 
theory says that heat from deep in the 
earth softens the rock under the crust 
and moves it around, disturbing the 
crust— and perhaps even spreading it. A 
few scientists even think some of the 
movements in the earth's crust may re- 
sult from the magnetic pull of other 
planets and nearby stars on the earth's 
iron core. 

Whatever the causes, we know that 
the surface of the earth will continue to 
change— sometimes rapidly, but most of 
the time so slowly that we are usually 
not aware of it.-MARGARET E. BAILEY 










Magma, or molten rock deep in the earth's crust, 
sometimes moves upward through cracks that don't 
reach the surface. With no outlet, the magma may push 
the surface layers of rock upward, forming dome moun- 
tains. In the background of this photo you can see the 
Henry Mountains in Utah, which are dome mountains. 





Where part of the earth's crust rises and lifts up 
flat layers of rock without folding or twisting them, 
a plateau is formed. In this photo of the Grand Canyon, 
which is part of the Colorado Plateau, you can see 
the flat rock layers of the plateau which have been 
exposed by erosion. 



-&P^ 




1 i ' i ' i ' i i i i 



11 ' ' r 



ss 



1 , I , T 



T=L 



i ' i'i " i 'i ' i f P= 



RTH' CKLST 

VULCANISM SHAPES THE EARTH ■B—b»»»^ 4 




"fcfc . 




n magma pours out through a crack in the earth's 
ace, the flowing rock— called lava— may spread over 
st area. Repeated lava "floods" pile layer upon layer 
>lcanic rock to form a high, flat lava plateau. The 
:o shows layers of lava rock (basalt) that form the 
mbia Plateau in the northwestern United States. 



In some places lava and cinders pile up 
around openings in the earth's surface, 
forming the mountains we call volcanoes. 
This photo shows the volcano Fujiyama 
in Japan. Many islands are the tops of 
undersea volcanoes. 




HASTROPHISM SHAPES THE EARTH 





nents (particles of rock and of animal and plant remains) 
pile up in places where the crust has been pulled down by 
rbances deep within the earth. Gradually the sediments 
;n into rock. Pressures inside the earth sometimes crumple 
old the layers of sedimentary rock. Over a long period of time 
s crumpled layers may be uplifted to form folded mountains. 
ihoto shows some of the curved layers of rock that have been 
d and pushed up to make Sheep's Mountain in Wyoming. 



Forces within the earth seem to push or pull the earth's crust, 
causing breaks, or faults, Ln the rock layers. If the movement 
is up and down, it may push surface layers upward on one side of 
the fault and downward on the other side, forming a fault-block 
mountain and valley. The Mormon Range, in Nevada, is a 
fault-block mountain. The flat land in front of the mountain 
is a fault-block valley. 





MAUNA KEA 



VOLCANO OBSERVATORY 







A BLOWS 
ITS 
COOL 



The island of Hawaii has been built by volcanoes 
through the ages. Kilauea, about 4,000 feet above 
sea level, is dwarfed by nearby Mauna Loa and 
Mauna Kea, both over 13,000 feet. 



After years of preparation, 
scientists were able to study the 
day-by-day events as a Hawaiian volcano 
erupted into fiery fountains of lava. 



■ A few years ago, scientists at the United States Geologi- 
cal Survey's volcano observatory in Hawaii began a race 
with a volcano. The volcano was Kilauea, and the observa- 
tory was perched near the edge of its crater, or caldera 
(see map). Scientists had been studying Kilauea for almost 
half a century. 

But they still needed to know many things. What was 
the underground "plumbing" of Kilauea really like? Where 
did the hot liquid rock inside the earth (called magma) 
come from? How did it get to the surface and spill out as 
lava? 

By answering these questions, the scientists might be 
able to predict the eruptions of Kilauea and of other vol- 
canoes. So they set out to study all of the details of a vol- 
canic eruption. They made plans to be ready when Kilauea 
erupted next. 

A Race with Kilauea 

For years, the scientists at the observatory worked to 
set up a network of seismographs — devices that record 
vibrations of the earth. Gradually they developed seismo- 
graphs that were specially suited to measure the earth- 
quakes within Kilauea. 

For a long time, scientists had known that the top of 
Kilauea swells before an eruption, with the sides of the 
volcano tilting outward slightly. So they developed instru- 

This article is adapted from Kilauea: Case History of a Volcano. 
/>v Don Herbert and Fulvio liardossi, published by Harper & Row, 
New York. Copyright © l ( X)H by Prism Productions, Inc. Printed 
by permission of the publisher. 

10 



ments called tiltmeters to measure these changes in 
Kilauea. Even as they made the tiltmeters and began using 
them, the scientists discovered that the surface of Kilauea 
was beginning to swell. 

A strange, quiet race began. The observatory team 
worked night and day, taking more tiltmeter measure- 
ments around the caldera. The measurements showed that 
the entire rim of the volcano was tilting outward. During 
November 1959, they found that the top of Kilauea was 
swelling at least three times faster than during the months 
before. Then earthquakes just below the caldera suddenly 
became 10 times more frequent and violent than before. 

On November 14, 1959, lava broke through a wall of 
Kilauea Iki, a smaller crater next to the main crater of 
Kilauea (see map). The eruption was on, and the ob- 
servatory staff now faced a great challenge and oppor- 
tunity—to use their skill and their instruments to discover 
the secrets hidden inside a volcano. 

Lava Lakes and Fountains 

Beginning at dawn on that November morning after the 
first outbreak, the scientists went to the lava fountains in 
Kilauea Iki. One group hiked to the edge of the crater 
floor, now covered with lava 1 5 feet deep. 

As they scrambled down the steep slope, the heat of 
the lava made them sweat. Puff's of smoke came from the 
ground around them — warning signals of underground 
pockets of pressure that could suddenly explode. The trail 
ended in a lake of flaming red lava. On the crater wall 
across the lake fountains of lava sprayed into the air ( see 

NATURE AND SCIENCE 



•I I 

I'l' 



Case History «|of an Eruption 

Here, in brief form, is the step-by-step history of Kilauea's 1959-1960 eruption, 
as pieced together from studies at the Hawaiian Volcano Observatory. 



1) Deep within the earth's mantle, about 37 miles below 
the Pacific Ocean, some of the molten rock (magma) 
mixed with steam and other gases. (What caused the 
rock to melt is still a mystery.) When the magma 
reached the great crack that is under the volcanoes in 
Hawaii, the weight of the layers of rock above it squeezed 
it upward. The magma streamed slowly toward the heart 
of Kilauea through channels in the rock and began to 
build up in an underground reservoir just a few miles 
below the caldera. Slowly the volcano's top began to 
swell as the reservoir filled with magma. 

KILAUEA'S TOP 
BEGAN TO SWELL 




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2) As the pressure of the magma in the reservoir in- 
creased, the rock began to give. There were many tiny, 
sharp earthquakes as the magma escaped from the 
reservoir and forced its way to the top. The pressure of 
the magma caused cracks that reached the surface, 
where the magma erupted as lava. 






M 



LAVA FOUNTAINS 




3) The eruption stopped when enough magma had 
escaped from the reservoir to lower the pressure that 
had forced the magma up to the surface. The eruption 
may also have been stopped by magma that hardened 
and formed a "plug" that blocked the route to the 
surface. 

KILAUEA'S TOP 
BEGAN TO SHRINh 




CHANNEL 



4) During the eruption, some magma from the reservoir 
flowed underground into an area of cracked rock (called 
a rift zone) far down the slopes of the volcano. (There 
was already magma in the rift zone from earlier erup- 
tions. As this magma cooled, it heated the rocks around 
it, forming a liquid core in the rift.) As new magma 
flowed into the rift zone, it increased the pressure on the 
rocks around the liquid core. Pressure also came from 
the swelling of the volcano's reservoir. Under this dou- 
ble "squeeze," the molten core forced the crust to give 
and lava poured out of breaks in the volcano's side. 
This was what happened at the Kapoho eruption (see 
text)- Since the lava poured out at a lower level than 
before, the pressure in the reservoir dropped quickly 
and the top of the volcano shrank. 

KILAUEA'S TOP 
CONTINUED TO SHRINK 













cover) . The scientists set up markers to measure the rise 
of the lava. Even as they worked the lava lake rose. 

In the days that followed, the scientists took measure- 
ments and kept records of as many aspects of the eruption 
as they could see— the directions and spread of lava, the 
height of fountains, how fast the lava flowed. At night, 

October 28, 1968 



men making temperature readings of the lava could be 
seen outlined against the glow of the volcano. 

On December 2 1 , the lava fountain sank from sight. But 
the top of the volcano was more swollen than ever. Some- 
where within Kilauea, the magma was moving in a new 
direction. (Continued on the next page) 

11 



Kilauea blows Its C ool (continued) 

Soon there was a swarm of new earthquakes. The scien- 
tists located the main source of the quakes, 30 miles away 
at a small village, Kapoho, which was on Kilauea's side. 
Part of the land near Kapoho began to sink and the vil- 
lagers left on January 13. The eruption near Kapoho 
started that evening, and once again a leaping curtain of 
fiery lava came from the earth. Two days later the lava 
had flowed to the coast and began pouring into the ocean. 
Clouds of steam rose thousands of feet into the air. 

Ninety-seven days after the eruption began high atop 
Kilauea, it ended almost 30 miles away on the volcano's 
side. The scientists had had a rare chance to learn about 
the inner workings of the earth. After studying all of the 
information they had gathered, they had one of the most 
complete case histories of a volcanic eruption ever as- 
sembled (see diagrams on page 11). 

The scientists still cannot predict exactly what Kilauea 




Wearing aluminum-covered suits for protection from the 
heat, the scientists were able to edge close to the lava to col- 
lect samples and to take temperature readings. 

will do in the future. On August 22 of this year, for ex- 
ample, the Hiiaka crater of Kilauea erupted, sending lava 
75 feet into the air. The crater had not previously erupted 
in historical time. There are more questions to be answered 
and more work to be done. The scientists would like to 
know how a huge volcano grows from the flat ocean floor. 
They would like to chart the places where the magma 
comes from, and to understand the forces that act on it. 
The study of volcanoes like Kilauea remains one of the 
greatest adventures ahead for scientists who wonder about 
the mysteries under the earth's crust ■ 

12 




More and more pieces seem to be fitting togethe 
as scientists keep trying to solve— 

The 
World's 

BIGGEST 

Jigsaw 
Puzzle 

by Diane Sherman 



■ Were all the continents once joined together? Scientisl 
who study the earth are beginning to think so. They ar 
coming to believe that all the continents were once part c 
a huge land mass that split up into separate continenl 
about 200 million years ago and have been moving apai 
ever since. 

Does this seem hard to believe? It was for the scientisl 
who first heard of the theory of "continental drift" su£ 
gested in 1910 by a German named Alfred Wegener. Lik 
other geologists (scientists who study rocks), Wegener ha 
noticed how the continents seemed shaped like pieces of 
jigsaw puzzle. South America and Africa, especially 
looked as if they would fit together. North America an 
Europe seemed to match up, too. Wegener found he coul 
even fit in India, Australia, and Antarctica as part of th 
same huge continent (see map above). Surely, he felt, th 
could not be coincidence! 

Wegener offered other evidence that seemed to suppo 
his theory: Some land formations were the same on boi 
sides of the Atlantic. India, Africa, and Australia had tl 
same kinds of rock layers. Fossils of the same types of ear 
animals and plants were found in South America, Austr; 
lia, Antarctica, and India. This last fact seemed especiall 
strange. How could the same kinds of plants and anima 
evolve in places separated by thousands of miles of ocear 

Wegener wondered, too, about evidence showing th; 
far-apart places like Australia, South Africa, and Soul 
America had gone through an ice age at the same time. A 

NATURE AND SCIENCE 







Je evidence could be explained, he thought, if the con- 
nents were once joined together. In time, he said, they 
fiust have drifted apart to become the continents we know 
$>day. 

< Scientists argued about Wegener's ideas for years. Some 
sologists thought the notion of continents moving had 
lierit. Others thought it was ridiculous. Meanwhile, new 
vidence of many different kinds was discovered. 

fitting the Pieces Together 

I Wegener had said the shapes of the continents seemed 
b match up. But nobody had made a scientific study of the 
tetual outlines of the continents to see whether they really 
TOuld fit together. In 1964, Sir Edward Bullard did just 
tiat. Using a computer at Cambridge University in En- 
land to help him, he set about "lining up" the continents 
'here they fit best. He didn't try to match coastlines, be- 
cause those are not the real edges of the continents. (Coast- 
nes are carved by the sea and the wind. Besides, they 
hange over long ages. When large amounts of water are 
)cked up in glaciers, the sea level is lower. When glaciers 
pelt, the level of the sea rises.) 

The real edges of the continents are about 30 miles out 
«om the coastline. Out to this point, the land beneath the 
>ater slopes gently downward. Then it drops sharply two 
ules or more to the deep ocean floor. This drop is called 
le continental slope. It was the slopes of the different con- 
nents that Bullard hoped to match up. 

October 28, 1968 



The shapes of the continental slopes had already been 

determined by bouncing sound waves off the ocean floor. 

When Bullard tried to match up the shapes, he made a 

startling discovery. If North America, Greenland, 

and Europe were put down side by side, they 

would still fit together today. Africa and South 

America also lined up neatly. The accuracy 

of the fit was almost perfect! 

These findings interested Dr. Patrick M. 
Hurley, a Professor of Geology at Massa- 
chusetts Institute of Technology, in Cam- 
bridge. Dr. Hurley and other scientists 
working with him decided to test the idea 
further by comparing the rocks on opposite 
sides of the Atlantic Ocean. 
West Africa, they knew, has two kinds of rock un- 
derneath the soil. One kind, to the west, is at least 2,000 
million years old, and the other, to the east, is about 600 
million years old. There is a very definite dividing line be- 
tween the two kinds of rock. If Africa and South America 
were once joined together, then South America should have 
the same rock formations and the same dividing line. The 
way Bullard had fitted the continents together, the dividing 
line should come very near the city of Sao Luis in Brazil. 

Dr. Hurley asked geologists at the University of Sao 
Paulo in Brazil to collect rock samples from around Sao 
Luis. It took rime to gather and analyze the rocks, but Dr. 
Hurley learned that some rocks found to the west of Sao 
Luis were 2,000 million years old. Other rocks, collected 
east of Sao Luis, were 600 million years old. The rocks in 

(Continued on the next page) 




Areas of rock that is at least 2 billion years old (orange) and 
of rock about 600 million years old (gray) fit together, sug- 
gesting that South America and Africa may have been joined 
like this some 200 million years ago. 

13 



The World's Biggest Jigsaw Puzzle (continued) 

Brazil were the same ages as their African counterparts, 
and the dividing line came almost exactly where Dr. Hur- 
ley had expected to find it (see map on page 13). 

"Compasses" in Rock 

Even stronger evidence that the continents had moved 
apart was discovered by scientists studying the magnetism 
of tiny bits of iron in certain kinds of rock. You have prob- 
ably seen how the earth's magnetic poles attract the needle 
of a compass. In the same way, tiny bits of iron in melted 
rock tend to line up with the magnetic poles of the earth. 
When the rock hardens, these iron "compass needles" be- 
come frozen records that point to where the north and 
south magnetic poles were at the time when the rock 
formed. 

The magnetic poles are known to move around a bit, and 
the scientists thought the directions of "compass needles" in 
widely separated rocks of the same age should show where 
the north magnetic pole was when the rocks were formed. 

The "compass" rocks in North America seemed to show 
that the north magnetic pole had wandered over a wide 
path during the past few hundred million years. But the 
rocks in Europe showed a different path for the pole's 
wandering during that time! (See map.) 




"Compass" rocks in North America seemed to show that the 
north magnetic pole has wandered along the black line dur- 
ing the past several hundred million years, but European 
rocks showed a different path (colored line). Scientists now 
believe the pole didn't move much, but the continents may 
have been moving apart during that time. 

It seemed unlikely that the earth ever had two north 
magnetic poles wandering around in different paths. But 
what if the north magnetic pole had not moved far at all? 
What if it was the continents that had moved great distances 
during the past few hundred million years? The "compass 

14 



needles" in the rocks that were formed during that time 
would be lined up just as they are today. 

How Could It Happen? 

Ever since Wegener first came up with the theory of con- 
tinental drift, there had been one main reason why many 
geologists scoffed at the idea. For a long time, no one could 
figure out what force might be strong enough to split the 
continents apart. Wegener thought maybe it was a force 
related to the spinning of the earth. But he had no idea how 
such a force might work. 

Today, new evidence seems to explain how the con- 
tinents may have been moved apart. Winding through the 
oceans of the world is a huge undersea mountain range, 
called the mid-ocean ridge (see map at right). A deep crack, 
or rift, 30 miles wide in places, runs the length of the ridge. 

The temperature of the sea bottom is slightly higher in 
the rift and along the ridge than it is along the sides of the 
ridge. Geologists think that hot, almost-melted rock is 
slowly but continually coming up through the rift. As more 
rock rises and hardens, it keeps pushing the sea floor out- 
ward from the rift on both sides. This kind of constant pres- 
sure might have split the continents apart and pushed them 
to where they are today. 

We know that the earth underneath the rift is unstable. 
Many earthquakes occur along the rift, and volcanoes 
spout up there, too. In the past four years, whole new is- 
lands have been formed near Iceland by lava pouring out 
onto the sea floor. 

Patterns in the Sea Floor 

There seems to be no question that hot rock is pouring 
out along the rift. But how do we know it pushes the ocean 
floor outward from the rift? Some evidence was recently 
discovered in the rock along the sides of the mid-ocean 
ridge. Scientists found a striped pattern in the magnetism of 
this rock. The stripes run parallel to the ridge, and the 
"compass needles" in each stripe are lined up in the oppo- 
site direction from those in the stripes next to it. The stripes 
are of different widths, and they are arranged in the same 
order on both sides of the ridge (see diagram on next page). 

We know that the polarity of the earth's magnetic field 
has been reversed nine times in the past 3.6 million years. 
(If this happened today, what we call the "north-seeking" 
end of our compasses would point to the south magnetic 
pole.) This would explain why rock that formed at the rift 
at different times was magnetized in opposite directions. 
And the striped pattern seems to prove that this new rock is 
gradually pushed away from the mid-ocean ridge, spread- 
ing the sea floor. 

There is still more evidence to show the ocean floor has 
been spreading. Samples of the material lying on the sea 

NATURE AND SCIENCE 



• • « 




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Strips of rock along the rift have "compass needles" 
pointing in opposite directions, showing that new rock 
has been forming there and pushing older rock outward 
as the earth's magnetic poles changed polarity nine times 
in the past 3.6 million years. 




WW 



The colored area in this map 
shows the mid-ocean ridge, a 
huge undersea mountain 
range that winds through the 
oceans. The white line in the 
ridge is a crack, or rift, 
through which hot, new rock 
may be gradually rising from 
inside the earth and pushing 
the ocean floor apart. The 
black dots show where earth- 
quakes occur most often (see 
"The Faults of Earthquakes'' 
page 2). The brown dots show 
where active volcanoes are 
located (see "Kilauea Blows 
Its Cool," page 10). 



\W WWW \ \\ V^v 

W \ WWW \\\ \\\^ 

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OLDER ROCK 



4- 4- 



NEW ROCK 



t 



bottom have been collected. This material, called sediment, 
is laid down very slowly. Year after year the shells of dead 
sea animals drift to the bottom. Silt washed to the sea by 
rivers may get mixed in. Ash from volcanic eruptions floats 
down. Gradually a thick layer of sediment builds up. 

Along the highest part of the mid-ocean ridge, in a strip 
100 to 150 miles wide, the sediment is very thin. Under- 
water photography often shows no sediment on this area at 
all. The absence of sediment may mean that this part of 
the ocean floor is new, and hasn't had time to accumulate 
a covering. 

Fossils provide evidence, too. The fossils in sediment 
taken from some parts of the Atlantic floor are much older 
than those in sediment from other areas. Geologists think 
the sections of the floor where no ancient fossils were found 
may be newer. 

The Search for Proof 

Sir Edward Bullard's map, Dr. Hurley's matching rocks, 
magnetic maps, and ocean sediments— taken together, they 
seem to show that Wegener's theory of wandering con- 
tinents was right. In the past year most scientists have come 

October 28, 1968 



to accept the idea of continental drift. But an attempt is 
now being made to prove the matter once and for all. 

The project is called JOIDES (for /oint Oceanographic 
/nstitution for Deep Earth Sampling). In over 50 separate 
ocean locations, a ship will send down a new, specially con- 
structed drill through four miles of water into the sediment 
below. In some places, the drills may dig as far as 2,600 
feet into the earth's crust to bring up samples of sediment 
and rock. Scientists will examine the samples, and try to 
determine which ones are oldest. If the ocean floor has 
really spread out from the mid-ocean ridges, then the oldest 
sediments should be from the northwestern part of the 
Pacific, or from the Caribbean, because those are the 
regions farthest from the ridges. 

Scientists aboard the drilling vessel are also measuring 
the heat coming up from the ocean bottom, investigating 
the magnetic patterns in rocks, and studying the formation 
of islands and undersea mountains. With enough informa- 
tion from enough different places, they may be able to say 
positively that the continents have split apart. 

Should that happen, one of the biggest scientific myster- 
ies of recent years can be marked "Case closed" ■ 

15 



prepared by DAVID WEBSTER 




MYSTERY PHOTOS 

The shadow of one 
matchbox was made by 
sunlight. The other 
shadow was made by 
light from an electric 
bulb. Can you tell 
which is which? 




FOR SCIENCE 
EXPERTS ONLY 

Why does the sun 
often appear to be 
almost round at sun- 
rise, but egg-shaped 




CAN YOU 
DOIT? ' 
Can you make some 
ice inside your 
house without using 
the refrigerator or 
freezer? 



JUST FOR FUN 

Put a penny in a little household 
ammonia in a covered jar as shown 
(Be careful not to touch or sniff 
the ammonia.) In a short time the 
ammonia should begin to turn 
a beautiful shade of blue. 
See if the color changes faster 
if part of the penny is sticking 
out of the ammonia. 




ANSWERS TO BRAIN-BOOSTERS IN THE LAST ISSUE 



Mystery Photo: The Mystery Photo shows a small water- 
fall, only a few inches high. 

What would happen if? The marble would travel in a 
straight line (path C) after it rolled off the plate. Would 
the marble travel in a curved path if the plate were on a 
slanted tabletop? 

Can you do it? It is possible to swallow water while you 
are upside down. Muscles in your throat contract and 
force the water up into your stomach. Why must birds 



lift their heads in order to swallow? 

Fun with numbers and shapes: The minute hand of a 
clock passes the hour hand only 11 times in 12 hours. 
For science experts only: Air pressing down on the news- 
paper would tend to keep the covered end of the yard- 
stick in place while the other end of the yardstick is 
forced down by your hand. Since one part of the yardstick 
stays still while the other part is moving, the yardstick will 
break if you hit it hard enough. 



16 



NATURE AND SCIENCE 



Using This Issue . . . 

(continued from page 2T) 

weaker until it disappears completely, 
then begins to get stronger in the oppo- 
site direction. By studying the direc- 
tions of "compass needles" in rocks 
formed at different times and places, 
scientists have found that the polarity 
of the earth's magnetic field has re- 
versed nine times in the past 4 million 
years, staying the same for periods 
ranging from about 50,000 years to 
about 850,000 years, and taking some- 
thing like 5,000 years to make a com- 
plete reversal. The reversal of polarity 
may be caused by some difference in 
the motions of the earth's mantle and 
core (which might be explained by the 
Rouse-Bisque theory suggested on 
page 4 of this issue). 

• If your pupils wonder what 
causes new rock to rise up in the mid- 
ocean rift and push the older rock on 
both sides farther from the rift, they 
are not alone. Scientists wonder, too. 
Some think that the rock in the mantle 
acts something like Silly Putty, which 
"flows" under the force of gravity with- 
out seeming to become any less solid. 
According to this theory, the mantle 
rock slowly circulates in giant convec- 
tion currents, moving slowly upward 
where it is hot and moving downward 
where it is cooler (see diagram; also 
"Brain-Boosters: Just for Fun," N&S, 
Oct. 14, 1968, page 4T). 




In giant convection currents, hot rock may 
be rising in the earth's mantle at the Mid- 
Atlantic Ridge (A), slowly moving west- 
ward under the American continents, and 
moving downward where it meets similar 
rock moving eastward from the East Pa- 
cific Rise (P). This apparent downward 
movement at the western coast of South 
America might be the cause of the folded 
mountains and of the faults that cause 
earthquakes in that area. 

October 28,1968 



Brain-Boosters 

Mystery Photo. The matchbox 
shadow with even shading and 
"sharper" edges was cast in light from 
the sun. Your pupils can discover this 
by comparing the shadows cast by a 
matchbox, or similar object, ( 1 ) in 
light from the sun, then (2) in light 
from a bright bulb within a few feet of 
the box. Can anyone explain why the 
bulb-light shadow is so much "fuzzier" 
at the edges than the sunlight shadow? 

By moving the light bulb farther 
away from the box, your pupils can 
make its shadow less and less "fuzzy" 
at the edges, until it is nearly as evenly 
shaded and "sharp-edged" as the 
shadow made in sunlight. 

When the bulb is close to the box, 
light from some parts of the bulb 
reaches into some of the areas shaded 
by the box from light from other parts 
of the bulb. This produces the mixture 
of light and shade that makes the edges 
of the shadow appear "fuzzy." While 
the sun is immensely bigger than the 
light bulb, it is so far away that the box 
blocks light from all parts of the sun 
from the shaded area. 

What would happen if? Obtain some 
wooden blocks of various shapes and 
let your pupils float them in a pan of 
water, observing their different orien- 
tations. A long block made of two 
cubes will float as shown here. 




Can you do it? To make ice without 
a freezer, put a small jar in the center 
of a pan and pack ice around it. Pour 
a large amount of salt on the ice, taking 
care not to get any in the jar. Then put 
a little water into the jar, and wait 
about 1 5 minutes for it to become ice. 

No amount of ice alone would be 
sufficient to freeze the water in the jar. 
Adding salt, however, lowers the melt- 
ing point of the ice, making it melt 
faster than it ordinarily would. The 



heat needed to melt the ice comes in 
part from the water in the jar, which 
drops in temperature as it gives up its 
heat. In time the ice melting in the pan 
takes enough heat from the water in 
the jar to cause it to freeze. 

Fun with numbers and shapes. After 
the orange juice and milk have been 
mixed as directed, each liquid will 
contain an equal amount of the other 
liquid. This holds true no matter how 
much of either liquid you start with. 
For example, if one pan contains 2 
cups of milk, pouring 1 cup of juice 
into it makes 3 cups of a mixture that 
is one-third juice and two-thirds milk. 
A cup of this mixture must then be 
made up of V3 of a cup of juice and 
% of a cup of milk. So pouring 1 cup 
of the mixture into the juice gives it 
% of a cup of milk and leaves % of 
a cup of juice mixed with the milk. 

Have your pupils figure out what 
fraction of a cup of each liquid will end 
up in the other liquid if they start with 
1, 3, 4, or some other number of cups 
of milk. (Someone may notice that the 
fraction always equals the number of 
cups of milk you start with divided by 
that number plus 1.) 

For science experts only. During 
the day, air that has been warmed by 
the sun rises, pushing aside the cooler 
air, and producing currents in the 
atmosphere. By sunset, there are many 
moving masses of air at different 
temperatures. The warmer and cooler 
masses of air bend, or refract, the sun- 
light differently because of their dif- 
ferent densities. This often makes the 
sun appear to be oval, or sometimes 
other shapes. At dawn the sunlight 
travels through cool air that bends all 
the light rays in about the same way, 
so the sun usually retains its normal 
round appearance. 

You can demonstrate the bending 
of light by standing a ruler in a glass 
of water. The bending of light passing 
from the denser water to the less dense 
air will make the ruler appear to be 
bent. 

Just for fun. If you do this in class, 
remember to caution the children 
against touching, tasting, or sniffing 
the ammonia. The blue color will ap- 
pear faster if part of the penny is 
exposed to the air. 

3T 







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nature and science 

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These two guides, one an excellent reference guide to 
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reproduce, and die. 

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This handbook, the first volume in the new NATURE AND 
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but seldom understand. 
This anthology of machines will answer 
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SNOW STUMPERS 

by David Webster 

(96 pages; 102 mystery photographs; 

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A new collection of mystery photographs, 
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NATURE AND SCIENCE 




nature and science 

TEACHER'S EDITION 

VOL. 6 NO. 5 / NOVEMBER 11, 1968 / SECTION 1 OF TWO SECTIONS 

COPYRIGHT © 1968 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 



USING THIS ISSUE OF NATURE AND SCIENCE 
IN YOUR CLASSROOM 



nature - — 
science 



Biological Birth 
Certificates 

Most of the methods developed for 
finding the age of animals are applied 
to fish and game. By determining the 
ages of a sample of an animal popula- 
tion, state fish and game departments 
are better able to regulate the "har- 
vest" of the animals. The information 
can also measure the success of game 
management methods; for example, to 
see how a change in vegetation has 
affected an animal population. 

Some methods of age determination 
are useful only for distinguishing 
adults from juveniles. Fish scales, 
however, not only reveal the animal's 
age in years but also indicate how fast 
the fish has grown during those years. 
An added advantage is that a scale 
can be removed from a fish and the 
animal can be returned to the water. 
In many other methods of age deter- 
mination the animal must be dead. 

Some methods of determining age 
are more accurate than others. Tooth 
wear, for example, may be affected by 
the kind of vegetation an animal eats. 
For this reason, the amount of tooth 
wear might be different in animals of 
the same age that come from different 
areas. 

Your pupils may wonder how the 
age of humans is determined (when no 
birth certificate or other record exists) . 
Suppose archeologists find a skeleton 
and want to find out how old the per- 
son was at death. Two useful clues are 
the emergence of adult teeth and the 
replacement of cartilage with bone. 



Both of these processes are completed 
in the early teens. After that, the shape 
and texture of the pelvic girdle pro- 
vides clues that enable scientists to 
determine the person's real age within 
four or five years. 



Discovering an "Ocean" 

Like Aesop's fables, this fascinat- 
ing Science Adventure story has a 
"moral": An idea that is accepted 
without being questioned or tested can 
he worse than no idea at all. 

Unlike Aesop, we left this conclu- 
sion for your pupils to draw for them- 
selves. You can help them by pointing 
out that Aristotle's idea— that every- 
thing was made of earth, water, fire, 
and air; that air had no weight; and 
that nature would not permit a vacuum 
(Latin for "nothingness") to exist— 
was accepted as "true" for nearly 
2,000 years. During that time people 
learned practically nothing about air 
or the earth's atmosphere. But once 
Galileo questioned the idea (even 
though he didn't disprove it com- 
pletely), scientists began investigating 
air and soon learned more about it and 
the atmosphere than people had dis- 
covered in all of man's previous ex- 
istence. 

This "snowballing" of knowledge 
has gone on at an ever-increasing pace 
since the time of scientists like Galileo 
and Torricelli, who were not afraid to 
question long-accepted ideas and test 
them against what really happens in 
nature. (Continued on the next page) 




IN THIS ISSUE 

(For classroom use of articles pre- 
ceded by • , see pages 1 T-4T.) 

Zoo Doctor 

A veterinarian tells some of the 
problems of treating patients of 
1,100 different species and trying to 
keep them all healthy. 

The Wonders of Wood 

By studying the structure of wood 
and combining wood with other 
materials, scientists have found ways 
to change its characteristics. 

• Biological Birth Certificates 

This Wall Chart shows some of 
the ways that scientists find the ages 
of animals captured in the wild. 

• Brain-Boosters 

• Discovering an "Ocean" 
from the Bottom 

Your pupils will learn how an Ital- 
ian mathematician opened a new 
field for scientific investigation by 
proving that we live in a "sea of air." 

Make the Most of Yeast 

A Science Workshop investigation 
into the reactions of yeast with dif- 
ferent foods. 



IN THE NEXT ISSUE 

How scientists are seeking ways to 
save elm trees from the Dutch elm 
disease... Science Workshops: In- 
vestigating how cells get food 
through their "skins" (osmosis), 
and the splash patterns of falling 
raindrops . . . Wall Chart on the 
physics of fasteners. 






Using This Issue . . . 

(continued from page IT) 

Topics for Class Discussion 

• Why was Aristotle's "no vacuum 
allowed" idea accepted for such a long 
time? Aristotle was a keen observer of 
the things around him, both living and 
non-living. In addition, he invented 
the system called logic— reasoning that 
if one thing is so, then certain other 
things must also be so— which is the 
basis for modern science. He was con- 
vinced that "true" ideas could only be 
found through logical reasoning, and 
he tended to trust ideas reached in that 
way without trying to make sure that 
the ideas really described what hap- 
pens in nature. 

Aristotle's ideas were accepted as 
"true" for the next 2,000 years, dur- 
ing which few people even learned to 
read and write, and the few who 
learned more than that studied under 
teachers who accepted Aristotle's 
ideas. 

You might point out that even Gali- 
leo didn't question the "no-vacuum" 
idea until he found out what miners 
had known for centuries— that a lift 
pump could only lift water about 30 
feet. Using Aristotle's logic, he rea- 
soned that if nature would not permit 
a vacuum to exist, then a lift pump 
should be able to lift water to any de- 
sired height. Again by logic, he rea- 
soned that nature's ability to prevent 
a vacuum must be limited by the 
weight of water, which seemed to 
make a column of water more than 33 
feet high fall apart. Galileo died be- 



NATURE AND SCIENCE is published for The American 
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nightly September, October, December through March; 
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Second Class postage paid at Garden City, N.Y. and at 
additional office. Copyright ® 1968 The American 
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fore he could test this idea, but Torri- 
celli, one of his students, questioned 
both Aristotle's idea and Galileo's 
modification of it. 

Torricelli used logic to figure out 
that if air has weight, and if the air 
pressing down on the earth is heavy 
enough to balance the weight of a 
column of water about 33 feet high, 
then it should also balance the weight 
of a column of mercury (which is 13.5 
times as heavy as water) about 30 
inches high. The barometer he in- 
vented proved his prediction was cor- 
rect, and this finding backed up his 
"sea of air" idea. 

• Besides stimulating other scien- 
tists to think and wonder about the 
air in new ways, why was the "sea of 
air" idea so useful to them? It served 
as a "model" of the atmosphere on 
which they could base their investiga- 
tions. For example, Pascal reasoned 
that if the atmosphere were like a 
"sea," then the higher you went in it, 
the less air there should be pressing 
down on you. His mountain-climbing 
experiment proved this so. 

In the same way, scientists today 
depend strongly on "models" — some- 
times actual physical models like the 
double-helix model of the DNA mole- 
cule or the "model" tornado shown in 
N&S, April 15, 1968, page 4, and 
sometimes idea models, like the "sea 
of air" idea. 

• Your pupils may wonder how 
Torricelli got the idea for his barom- 
eter. You might tell them this story: 

In 1641, two years before Torricelli 
invented the barometer, another Ital- 
ian named Gasparo Berti tried to 
create a vacuum in a 40-foot tube with 
valves at the top and bottom. He 
placed the tube so that its top was 
near a window in a tower of his castle- 
like home (see Diagram A). Then he 
filled the tube with water and closed 
the top valve. When the bottom valve 
was opened, some of the water flowed 
out, but not all of it. Berti closed the 
bottom valve and then opened the 
top valve from the tower window. 
Whoosh! Air rushed into the top of 
the tube. Berti had created a vacuum. 
He lowered a weight attached to a dry 
string through the tube, and found 
that the column of water left in the 



tube was about 34 feet high. This was 
at least a foot higher than the very 
best lift pump could lift water in a 
pipe. 

Obviously, the height to which a lift 
pump could raise water was not the 
most accurate measure of air pressure, 
so Torricelli adapted Berti's method 
of making a vacuum to measure air 
pressure with mercury. 

• Does the height of the mercury in 
a barometer tube measure the weight 
of the air that is pressing down on the 
entire surface of the mercury in the 
bowl, or reservoir? No. The weight of 
the mercury in the tube is supported 
(or "balanced," as on a balance scale) 
by the weight of a "column" of air the 
same diameter as the mercury column 
but extending from the surface of the 
mercury in the reservoir to the top of 
the atmosphere (see Diagram B). 

• How could you use a barometer 
tube whose opening was one square 
inch in area to find out how many 
pounds of air are pressing down on 
each square inch of your body? Mer- 
cury weighs about 0.49 pounds per 
cubic inch. If the top of the mercury 
in the tube is 30 inches above the res- 
ervoir surface, the column is made of 
30 cubic inches of mercury, which 
weighs 30 x 0.49=14.7 pounds. (The 
average atmospheric pressure at sea 
level is 14.7 pounds per square inch.) 

• Why do meteorologists measure 
atmospheric pressure in "inches of 
mercury," while engineers measure it 

(Continued on page 3T) 




lid V 



valve 




2T 



XATl'RE AND SCIt.S< I 



THT 



VOL. 6 NO. 5 / NOVEMBER 11, 1968 



?»«! science 



uan you 

live under a "sea" 

without knowing it? 

see page 10 

DISCOVERING 
AN "OCEAN" 
FROM THE BOTTOM 




nature and science 

VOL. 6 NO. 5 / NOVEMBER 11, 1968 



CONTENTS 

2 Zoo Doctor, by Steven Morris 
6 The Wonders of Wood, by Rod Cochran 
8 Biological Birth Certificates, 
by Susan J. Wernert 

10 Brain-Boosters, by David Webster 

1 1 Discovering an "Ocean" from the Bottom, 

by Robert Gardner 
14 Make the Most of Yeast, 

by Nancy M. Thornton 
16 What's New?, by Roger George 

PICTURE CREDITS: Cover, p. 3, p. 4 (left). New York Zoological Society 
photos by Sam Dunton; p. 4 (riyht). p. 5, by Plachy from Three Lions, Inc.; 
pp. 6-11, 13, drawings by Graphic Arts Department, The American Museum of 
Natural History; pp. 6. 7. photos from Rod Cochran; p. 8, photo courtesy of 
Illinois Natural History Survey; p. 9. horn photo from AMNH, bone photo by 
Leonard L. Rue III; p. 10, top photo by David Webster, bottom by Franklyn K. 
Lauden; p. 12, b> Robert Gardner: p. 13. photo by Franklyn K. Lauden; p. 14, 
barometer photo by Robert Gardner, yeast by Hugh Spencer; pp. 14-15, drawing 
by Donald B. Clausen; p. 16. top photo courtesy of U.S. Navy; bottom by R. J. 
Lefkowiiz. 



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<imiu#i ' 
II*i*iUh 

In his job as an "animal doctor" at a zoo, Dr. 
Charles P. Gandal finds himself operating on 
snakes, deciding what to feed young gorillas, 
and checking on the health of about 3,000 
animals from all over the world. 



by Steven W. Morri 



■ Gorillas with colds? A python sick with cancer? 

I had recently read of such things in reports written t 
Charles P. Gdndal, the "animal doctor" (veterinarian) 
the New York Zoological Park, which most people a 
"the Bronx Zoo." I decided to visit the zoo hospital, 
small white building most zoo visitors never see. 

The doctor's job there must be a big one, I thought. Tl 
zoo has about 3,000 animals of 1,100 kinds (species 
And caring for the animals that get sick each day is nj 
Dr. Gandal's only job. He must also make sure no diseasi 
are transferred to the animals from the more than t\s 
million people who visit the zoo each year. And whenevi 
a new animal comes in, Dr. Gandal must be sure it is n\ 
bringing germs or parasites that might be dangerous 
the animals it will be living near. The doctor also tries 
see that the animals are kept in surroundings that will he 



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NATURE AND SCIENCE 



ir 




k 



>ga, one of the young lowland gorillas raised at the 
onx Zoo, often showed affection toward Dr. Gandal. 



lem stay healthy. For example, Dr. Gandal once had a 
roblem with four young gorillas. 

irowing Gorillas 

Gorillas don't mate and reproduce nearly so often in 
dos as they do in the wild. Most gorillas that are in zoos 
'ere caught when they were very young, before they had 
luch experience in living with other gorillas. In the zoos 
ley are kept by themselves or sometimes in twos. As they 
fow they sometimes get on each other's nerves, and may 
ght. 

Would gorillas be able to get along with each other 
etter if they had more chance to play and live with other 
orillas when they were young? 

| To find out, the zoo got four baby lowland gorillas. The 
[reparations for their coming took weeks. During their 
rst four months, no one was allowed to go near them 
>ccept hospital staff and some keepers. 

November 11, 1968 



"We built sleeping boxes and put them across the backs 
of two big cages that had connecting doors.*' said Dr. 
Gandal. "The gorillas had plenty of room. The cage floors 
were deeply carpeted with wood shavings, and in one cage 
we put things for the gorillas to play with— rubber balls, a 
swing, a tire hanging by a rope. 

"What should we feed them? People arc wrong who 
think animals always know what foods to eat for good 
health. We decided to get the babies used to eating a kind 
of 'cake' that had been fed to apes in other zoos and had 
kept them healthy. It is a mixture of grain and other foods 
that contains all the vitamins, minerals, proteins, and 
starches that apes need for health. Usually we gave it to 
them along with vegetables and milk. Within a week, the 
little gorillas were eating the cake regularly. Another food 
they liked— perhaps because of the easy-to-hold shape- 
was carrots, which they liked to carry along as they ex- 
plored and played. Every now and then they would stop 
to nibble. 

"The babies didn't need much doctoring," Dr. Gandal 
said. "We knew they could easily catch human diseases 
such as colds and pneumonia, so even the zoo workers were 
warned to stay away if they had any signs of a cold or 
sinus trouble. Even so, all four babies had runny noses a 
couple of weeks after they came. Right away we made the 
cage warmer by about five degrees, and put in a vaporizer 
that sprayed water into the air, making it easier for the 
animals to breathe. This is the same treatment that your 
doctor might prescribe for you 

"On the third day, three of the gorillas were healthy 
and playing normally again. Only little Bendera. the 
smaller male, was slow and quiet and seemed not to have 
improved 

"I checked his pulse, body temperature, and breathing. 
He had a slight fever and his lungs were slightly 'stuffed 
up,' or congested. We gave him a sweetened germ-killing 
medicine that is often given to children with colds. His 
keeper saw to it that Bendera took his medicine every day, 
usually in a cup of specially sweetened milk. By the second 
day, Bendera was much better, and by the third he was 
playing with the others as usual. 

"Checking for other possible diseases, we found that 
the babies had parasitic roundworms inside them. There 
were only a few, and a little medicine got rid of them. The 
babies seemed content most of the time they were in the 
hospital and after they were moved to the ape house. If 
we can keep them that way, maybe years from now they 
will produce young," Dr. Gandal said. 

To Save a Snake 

If you visit the Bronx Zoo. you may see a 12-foot 

(Continued on the next page) 



Zoo Doctor (continued) 

Indian python (see cover). You will have to look close to 
see the 2Vi -inch scar under the snake's jaw. Dr. Gandal 
told me how it got there. 
"One day a keeper noticed a marble-sized swelling 




The zoo has a well- 
equipped hospital to 
care for its 3,000 ani- 
mals. Here Dr. Gandal 
examines an X-ray of an 
antelope's broken leg. 



under the snake's jaw. The lump kept growing. Soon we 
were treating the snake daily, making cuts to drain the 
liquid out of the lump, and giving the snake medicine." 

The medicine cleared up an infection caused by bacteria, 
but the snake's jaw kept swelling. Dr. Gandal cut a small 
piece out of the lump and examined it under a microscope. 
He discovered that the swelling was caused by the disease 
called cancer. 

By now the swelling had grown to the size of an orange. 
"We brought the snake to the hospital," Dr. Gandal said. 
"I put a tube down its windpipe and we pumped in a gas 
that 'knocked out' the snake. 

"The surgery to cut the lump out was bloody, long, and 
tiring. Ninety minutes after we started, I tied the last of 
more than 100 stitches. We kept giving the snake oxygen 
for more than two hours. The lump weighed 1 V2 pounds. 

"Of course, the snake couldn't eat after so much cut- 
ting," Dr. Gandal said. "We fed it by injecting liquid sugar 
and protein under its skin once a week. Thirteen weeks 
after the surgery, the reptile keepers excitedly told me that 
the python had eaten without help. It was well again." 

On the day I visited the zoo hospital I could tell some- 
thing unusual was happening. Dr. Gandal was peering 



Dr. Gandal and his assistant often use a 

microscope to examine blood samples 

taken from the zoo animals. 



into a microscope. A blackfoot penguin at the New York 
Aquarium had died mysteriously after acting strangely for 
three days. Dr. Gandal had been called to investigate. 

What Happened to the Penguin? 

Tests showed the penguin had died of malaria, a disease 
that kills by destroying an animal's red blood cells. This 
disease had never before been found at the aquarium. A 
bird catches the disease in the same way humans do, by 
being bitten by a mosquito that has taken malaria parasites 
into its body along with the blood of a diseased animal that 
it has bitten. Humans can't get the same type of malaria 
that penguins get, so there was no danger to visitors. How- 
ever, the disease could have been passed on to other birds 
in the flock. 

A small box near Dr. Gandal's microscope contained 
glass slides, each with a reddish smear on it. One by one, 
Dr. Gandal took out a slide, put it under the microscope, 
and moved it back and forth, searching. 

"These are samples of blood we took from the other 
birds in the flock," he said. "Look here." 

Through the lens I saw round red blood cells. Two of 
them had small darker red spots in them. "The bird we got 
this blood from has malaria," Dr. Gandal said. "We'll have 
to get it out of the flock right away." 

With the penguin separated from the flock, the malaria 
would spread no further. When Dr. Gandal had finished 
looking at the rest of the slides and arranged for the 




NATURE AND SCIENCE 




Besides caring for sick snakes and young gorillas, on a "typical" 
day Dr. Gandal may be found giving a pill to an elephant with an 
upset stomach (above), putting ointment on the eye infection of 
a tortoise (left), and examining an agouti for a possible lung 
infection (below). 






diseased bird to be taken out of the flock, he motioned for 
me to follow him on another job. 

Why Do Zoo Animals Die? 

We went to a small room next to Dr. Gandal's office. 
He opened a wooden refrigerator door set in a wall, walked 
inside, brought out some dead animals, and put them on 
a table. 

"When animals die they're put in here with a note telling 
me when they died and any other information I should 
know," he said. "I examine the bodies to find out exactly 
why they died. This gives us clues to any possible dangers 
to other animals." 

A king vulture had been sick for a long time before it 
died. It had refused to eat the dead mice that had been 
injected with medicine that might have helped it survive. 
The doctor first examined the vulture's head for signs of 
breaks in the skull. 

"That's often the cause of birds dying," he said. "When 
you see a big beak like that, you can imagine why. One 
bird will often whomp another one on the head." 

But this bird's head showed no signs of injury. Dr. 
Gandal then cut the bird's body open. Some of its organs 
were swollen. He cut pieces from them and put them in a 
jar to be sent away to a special laboratory to be examined. 

He did such autopsies, or after-death examinations, on 
a duck, two prairie dogs, a small, monkey-like demidoff 
galago, a king snake, two chipmunks, and a toucan. 




"See how discolored its liver is? Toucans often tend to 
develop liver disease," he said. 

I asked, "Do they in the wild too?" 

"We don't know. That's one of our troubles. We don't 
see many diseased animals in the wild, so we don't know 
how much of a zoo animal's illness is caused by captivity. 

"Like human medicine, doctoring of animals has had 
great changes since I came to the zoo, 17 years ago," Dr. 
Gandal said. "There have been new vaccines, medicines, 
and equipment. But it seems that no matter how advanced 
the techniques of medicine get, the good zoo doctor will 
still have to like animals, and understand them, to do his 
job well." ■ 



November 11, 1968 



*? 




As scientists learn more about 
wood, they are able to combine 
it with other substances to 
make new materials. 

by Rod Cochran HI 



■ Wood is one of the most useful materials man has found 
on the earth. It is strong, light, easy to work with, and 
can be stained, varnished, or painted in many ways. As 
scientists called wood technologists have studied wood and 
learned about its structure, they have begun to understand 
why wood is so useful. And the more they learn about 
wood, the more uses they find for it. 

You probably know already that tree trunks and limbs 
are made up of rings of wood, called annual rings. (The 
age of many kinds of trees can be discovered by counting 
their annual rings.) All of the wood in a growth ring is 
not the same; the wood that grows rapidly in the spring 
is not as dense or as strong as the slower-growing summer 
wood (see diagram). 

By examining wood with microscopes, scientists have 
found that wood is made up of long, hair-like cells called 
tracheids {see photo). A one-inch cube of Douglas fir wood 
may contain three million of these long cells. The tracheids 
are cemented together with a tough "glue" called lignin. 
The walls of the cells are made up mostly of another 
strong material, called cellulose. Wood is about two-thirds 
cellulose and one-third lignin. 

Using powerful electron microscopes, scientists have 
been able to examine a single tracheid. They found that 
each tracheid has walls made up of three layers, with tiny 
strands of cellulose locked in different directions in each 
layer. This makes the cell wall especially strong for its size. 

Chemists can separate the cellulose fibers from the lignin 
th;it holds them together. This is the first step in paper 



SUMMER 
GROWTH 



SPRING 
GROWTH 



The light-colored part of 
a tree's annual rings grows 
rapidly, in the spring. The summer 
growth is slow and dark colored. 



A microscopic view of a 
tiny block of wood would 
look something like this. 
The long cells are called 
tracheids. The rays are 
bands of cells that grow 
out from the center of a 
tree like the spokes of a 
wheel. 



TRACHEID CELLS 




RAYS 



making. The fibers are then arranged in a layer and pressed 
into paper. Tear a piece of newspaper and hold it up to 
the light. You can see the fuzzy cellulose fibers along the 
torn edges. Cellulose fibers are used in such materials as 
plastics, rayon, and photographic film, and in the pages 
of this magazine. 

Mixing Wood and Plastic 

After wood has dried, liquids can be forced into the 
hollows where watery sap once was. Some liquids preserve 
wood for many years. Others can make it fireproof, or 
insect-proof. Technologists recently discovered that they 
can force liquid plastic into wood, then harden the plastic 
into a solid by heating. 

VATURl i\n s ( ii \< I 








11.11 r 1 


■i, h^r ■ 




1 iL, 


T^^o 


• 


Wr^^> 


111 



This is the machine used by 
Dr. Siau to measure the com- 
pressive strength of wood. 
The arrow points to the piece 
of wood being tested. The dial 
near Dr. Siau shows the 
amount of pressure the ma- 
chine is putting on the wood. 



One of the men studying this new wood-plastic com- 
bination is Dr. John Siau of the State University College 
of Forestry at Syracuse, New York. His job was to find out 
how the plastic changes the properties of the wood. 

One test compared the strength of a piece of basswood 
with an equal-sized piece of a basswood-plastic combina- 
tion. Dr. Siau put a sample of basswood into a testing 
machine that can push on an object with as much as 
120,000 pounds of force. (The machine measures what is 
called the compressive strength of objects.) Slowly the 
great machine began to press down on the wood. The hand 
on a large dial began to move, showing the amount of 
pressure. The piece of basswood was one inch square and 
four inches long. It supported five tons— the weight of three 
automobiles— before it broke. 

When Dr. Siau tested an equal-sized piece of basswood- 
plastic, he found that its compressive strength was twice 
that of basswood alone. (Can you figure out why?) 

Dr. Siau also found that wood-plastic is a better con- 
ductor of heat than wood alone. In another test, he mea- 
sured the stiffness (rigidity) of the two materials. 

This time each sample was hung in the air by threads. 
Then a high-pitched sound was aimed at the samples, 
causing them to vibrate. A device called an oscilloscope 
measured the frequency of vibrations. The stiffer a mate- 
rial, the more rapidly it vibrates. Dr. Siau found that the 
wood-plastic was more rigid than the wood alone. 

Since wood technologists have learned about the char- 
acteristics of wood-plastic, they have found many uses 

November 11,1968 



for this new material. It is being used for billiard cues, 
flooring, knife handles, table tops, and chair arms. 

By learning more about the structure of wood and by 
combining wood with other substances, technologists 
hope to find new uses for this abundant, cheap material. 
For example, the lignin that makes up about a third of 
wood is usually thrown away as waste. Wood chemists are 
searching for ways to use lignin and add to the 5,000 ways 
in which wood is already used by man ■ 



PROJECT 



You can test the stiffness of different kinds of wood 
by using a vise and a spring balance as shown in the 
diagram. Be sure to use wood samples of the same 
size, and be sure that the vise grips an equal length 
of each sample. As you pull on the balance (see 
diagram), watch to see how much force is needed to 
break each stick. Weigh the wood samples before- 
hand. Are the heaviest kinds of wood always the 
strongest? 





Qiodoqicad ^Bt/ttfc ft 



MEASUREMENT 

Length, height, and weight often reveal whether 
one animal is older than another. But measure- 
ments like these don't always depend on age 
alone. They are also affected by such things as 
the amount of food available, the animal's activi- 
ties, and even the temperature of the animal's 
surroundings. Also, many parts of an animal stop 
growing when a certain age or size is reached. 

In many animals, however, the lens of the eye 
grows throughout life. It apparently isn't affected 
by food or other factors that usually affect an 
animal's size. The weight of the eye lens is now 
used to find the age of cottontail rabbits, black 
bears, raccoons, and seals. The photo shows a 
lens (held on forceps) that was taken from the 
deer's eye on the right. 




FEATHER TIPS 
LIGHT COLORED 



FEATHER TIPS 
COLORED THE SAME 
AS THE REST 
OF THE FEATHERS 



WING OF YOUNG QUAIL 



WING OF ADULT QUAIL 



The feathers that grow on a bird during its first year often 
look very different from the feathers that replace them. 
Many ground-living birds, such as quail and pheasant, shed 
their wing feathers one by one in a certain order. A bird's 
age can be figured out by seeing which feathers have been 
shed and replaced by adult feathers. Once a bird has all of 
its feathers, biologists have to look for other clues to its age. 



cj? "How old are you?" can often be answered by 
a biological birth certificate. This record is not kept I 
on paper — it is "written" into the structure of an j 
animal. 

Biologists have a number of ways of finding the 
ages of animals. Each method was worked out by 
studying animals whose ages were known (such! 
as those born in zoos). This Wall Chart shows 
some of the ways in which scientists find an ani- 
mal's age. 

Once biologists know the ages of some of the 
animals from a population (a group of animals of 
the same kind living in an area) , they have some 
idea of how the population is doing. If most of the 
population is old, for example, biologists know 
that the population is in danger of dying out. If the 
population includes many young, however, it 
means that the animals are reproducing well and 
may be increasing in numbers. This kind of infor- 
mation is especially useful to biologists who study 
populations of animals that are hunted and fished. 
It helps them set hunting and fishing seasons and 
other rules so that the animals don't become either 
too scarce or too abundant. -Susan J. Wernert 



DEVELOPMENT 




As an animal gets older, there are often changes in the 
shape, color, and numbers of parts of its body, such as 
teeth. Any of these changes can be a good clue to the age 
of an animal if biologists know that the change occurs 
at the same time in the life of most animals of the same 
kind. 



Teeth reveal the age of deer, antelope, moose, and horses, 
The ages of the youngest animals can be determined by seeing 
which "baby" teeth they have. To find the age of slightly 
older animals, biologists see how many "baby" teeth have 
been replaced by permanent teeth. Finally, they look at the 
amount of wear on the grinding teeth— the premolars and 
molars. (People once thought that the number of points on 
a deer's antlers revealed its age, but the size of a deer's antlera 
depends mainly on the amount and kind of food it eats.) 



■COUNTING THE YEARS 



The rate of growth of many animals changes from season 
to season. A drop in temperature during the winter can 
slow the growth of a fish. A limited food supply in the 
winter slows the growth of other animals. And, for still 



other animals, growth may slow down during the breeding 
season. Luckily, these changes in the rate of growth often 
show up in an animal's body, and the animal's age can be 
discovered by counting the different growth marks. 




The scales of most kinds of fishes bear 
rings that reveal the age of the animal. 
The scales grow by adding rings in the cen- 
ter. The quicker growth in the summer 
produces more and wider rings than the 
slow winter growth. The drawing shows a 
scale from a four-year-old bluegill sunfish. 
In what year of its life did the fish grow the 
most? 



HORN OF 
DALL'S SHEE? 



The horns of animals like 
bighorn sheep and moun- 
tain goats often reveal 
their ages, for the winter 
slowdown of growth causes 
deep grooves on the out- 
side of the horns. But the 
age of the females is hard 
to tell; the rings on their 
horns are much less clear 
than the rings on the males' 
horns. 




THE DEEP GROOVES 
ARE WINTER 
GROWTH MARKS 










LARS ARE 
"' TEETH 



LOWER JAW 
\, OF DEER 
ONLY ONE *>W '" 

MOLAR TOOTH v 

- 6 MONTHS 




lVz YEARS 



REMOLARS 
LIGHTLY 
' DOWN 



POINTS ON FIRST 
MOLAR NEARLY 
WORN AWAY 




9'/ 2 YEARS 









An animal's bones are often a clue to its age. Limb bones are 
first made of a soft material called cart/7age. As an animal grows 
older, more and more of its cartilage is replaced by hard bone. 
To find the age of some small animals, biologists check to see 
how much of their limb bones is still cartilage. But all of the 
cartilage in the bones of these animals is replaced within one or 
two years after birth, so only the age of younger animals can be 
found in this way. 




!5 HUMERUS BONE 



FROM RABBIT 
THAT WAS LESS 
THAN 9 MONTHS OLD 





. ■ 





WHAT WOULD HAPPEN IF . . . 

. . . the three containers were filled with 
hot water as shown? Which one would 
cool off fastest? 




FUN WITH 

NUMBERS 
ANQ SHAPES 

Each letter in this 
addition problem 
stands for a dif- 
ferent number. 
Can you substi- 
tute the proper 
numbers to make 
the answer cor- 
rect? 



ABCV 

ABCV 



Submitted by 
Steve Painter. South 



ANSWERS TO BRAIN-BOOSTERS IN THE LAST ISSUE 



JUST FOR FUN 

Here is how to make bubbles float 
in "mid-air." Close the drain in a 
bathtub or large sink and dump in 
a box of baking soda. Then pour in 
a bottle of vinegar and add some 
water. The bubbling shows that 
carbon dioxide gas is being formed. 
Now blow soap bubbles and let 
them drop into the sink. The bub- 
bles should float on the layer of car- 
bon dioxide until they break. 



BAKING SODA 
VINEGAR AND WATER 





What would happen if? Here 
is how the long wooden 
block would float. Would a 
square block made from four 
small blocks float this way? 





Can you do it? To make ice 
without a freezer, put a small 
jar in the center of a pan and 
pack ice around it (see dia- 
gram). Pour a lot of salt on the 
ice. (Don't get any salt in the 
jar.) Then put a little water in- 
to the jar. You should have 
some ice after 1 5 minutes. Can 
you make ice this way without 
using any salt? 



Mystery Photo. The matchbox shadow with the 
"sharper" edges and even shading was made by light 



from the sun. Can you figure out why the shadow 
made in light from a bulb had such "fuzzy" edges? 



Fun with numbers and shapes: After the milk and 
orange juice are mixed, the amount of milk in the 
orange juice is the same as the amount of orange 
juice in the milk. Can you figure out why? 

For science experts only: During the day, the air 
that has been warmed up by the sun rises, and 
pushes aside the cooler air. By sunset, there are 
many moving masses of air at different tempera- 
tures between your eyes and the sun. The warmer 
and cooler masses of air bend the light in different 
ways, often making the sun appear to be oval, or 
sometimes other shapes. At dawn the sunlight 
reaches your eyes through cool air that bends all 
the light rays in about the same way, so the sun's 
round shape does not usually appear changed. 



prepared by DAVID WEBSTER 



SATURE AND SCIENCE 



Discovering an "OCEAN 
from the 



™ 



When an Italian mathematics professor 
tried to explain how a lift pump works, he 
discovered that we live at the 
bottom of a "sea of air." 

BOTTOM 

by Robert Gardner 



■ Have you ever thought that people living on earth are 
like fish that live at the bottom of the ocean? This idea was 
suggested over 300 years ago by an Italian mathematics 
professor named Evangelista Torricelli. He said that we 
live at the bottom of a "sea of air," and that the weight of 
the air in this "sea" is constantly pushing on us just as the 
water in the ocean pushes on a fish or on a deep-sea diver 
walking on the ocean floor. 

Torricelli got this idea in the early 1600s after one of 
the world's greatest scientists, Galileo Galilei, noticed 



something that men who worked in mines had known for 
a long time. The best of the lift pumps (see diagram) used 
to pump water out of mines would not lift water more 
than about 33 feet above the surface of a water pool. 
Galileo's discovery alarmed most scientists, because the 
operation of lift pumps had always been explained by an 
idea suggested by Aristotle, an early Greek scientist. 
Aristotle had said that nature abhors, or won't permit, a 
vacuum. Therefore, scientists in the early 1 600s believed 
that water rushes in to fill the space below the rising piston 
of a lift pump because if it didn't, a vacuum would be 
created. (Continued on the next page) 



PROJECT 



Fill a straw with water and keep your finger firmly 
over the top. Does the water run out? Try to suck the 
air from a straw with its other end in a liquid. What 
happens? Does the same thing happen if you first 
punch a hole in the side of the straw above the level 
of the liquid in the glass? How could the idea that 
"nature abhors a vacuum" be used to explain these 
things? 





A. Pushing down the handle of a lift pump raises the 
piston in the pump chamber. Air pressure keeps the 
piston valve closed, so the rising piston lifts air out 
of the chamber and water from a well or pool rises 
through the intake pipe and valve into the chamber. 

B. Pulling the handle up pushes the piston down, 
and water pushes through the piston valve into the 
chamber above the piston. C. When the piston is 
lifted again, the water above it is pushed out of the 
spout. 

• Lift pumps were used in many kitchens as late 
as 50 years ago to draw water from a shallow well. 
But few lift pumps can lift water higher than about 
30 feet above the surface of a pool. (Can you guess 
why?) See if you can figure out a way that several 
lift pumps could be used to pump water out of a 
mine that is, say, 100 feet deep. 

• Usually you have to "pump" the handle up and 
down several times before water starts to flow out of 
the spout. Can you guess why? 



11 



Discovering an "Ocean" (continued) 

Galileo realized that Aristotle's idea could not explain 
why a lift pump could not raise water more than 33 feet 
or so. He suggested another explanation: Perhaps a col- 
umn of water more than 33 feet high was not "strong" 
enough to hold up its own weight. 

Gajileo probably never tested this idea, but we know 
it was wrong. When a lift pump is used at a high place, 
such, as a mine in the mountains, it cannot lift water even 
33 feet. The higher the location, the shorter the distance a 
lift pump can liff: water. Galileo's idea could not explain 
this unless water weighed more on a mountain than near 
the sea. But water actually weighs a bit less the farther it 
is from the center of the earth. (Can you guess why?) 

Torricelli did not know about this, but he disagreed with 
both Aristotle's and Galileo's explanations anyway. He 
knew that the deeper we go in water, the more water there 
is pressing down on us, and that the water pushes upward 
as well as sideways and downward- (If water didn't push 
upward, would a block of wqod float in it?) 

He also knew, from experiments done by Galileo, that 
air has weight, just as water does. So Torricelli reasoned 
that the air surrounding the earth is like a sea, and that 
we live at the very bottom of it, with the weight of the air 
pushing downward, upward, and sideways on us and 
everything else. 

He argued that this "sea of air" could not push water 
up inside a tube that was open at the top because the air 
is also pushing downward through the tube. But when the 
air in a tube is removed by means of a lift pump at the 
top, the sea of air pushes the water at the bottom of the 
tube up into it. 

Torricelli knew that mercury is 13V2 times as dense as 
water; that is, a volume of mercury weighs 13Vi times 
more than an equal volume of water. (See "How Dense Are 
You?", N&S, September 30, 1968.) So he figured that a 
lift pump should be able to lift mercury only about 30 
inches. (How did he figure this out?) To avoid using 
very long tubes, Torricelli used mercury instead of water 
in his experiments. 

The First Barometer 

While testing his "sea of air" idea in 1643, Torricelli 
invented an instrument that enabled him to measure air 
pressure. He took a three-foot glass tube that was closed 
at one end, and filled it with mercury. He held his finger 
over the open end of the tube and placed it below the 
surface of some other mercury in a shallow bowl. Then he 
removed his finger and slowly lifted the closed end of the 
tube until the tube stood straight up in the mercury. As he 
lifted the end of the tube, some of the mercury fell out into 
the bowl, leaving an open space in the top of the tube. 
But when the top of the mercury was about 29 to 30 inches 
12 



above the surface of the mercury in the bowl, it stayed at 
that height in the tube, just as Torricelli had predicted (see 
photos). 





Torricelli made the first barometer like this: He filled a glass 
tube (closed at one end) with mercury, placed the open end 
in a bowl of mercury, and lifted the closed end (left photo) 
until the tube stood straight up in the mercury. As the tube 
was raised, some mercury dropped back into the bowl, 
leaving a vacuum in the top of the tube (right photo). The 
height of the mercury in the tube above the surface of the 
mercury in the bowl provides a measure of the weight of air 
that is pressing down on the mercury in the bowl. 

He knew that no air bubbles had gone up the tube, so 
the space above the mercury must be empty. While invent- 
ing a device to measure air pressure, Torricelli had also 
found a way to create a vacuum. 

Torricelli found that sometimes the height of his mer- 
cury column moved up or down as much as an inch or so 
from one day to the next. He believed that the air pushing 
on the mercury in the bowl kept the mercury from falling 
out of the tube. When the air pressure got stronger, more 
mercury was pushed up the tube; when the air pressure 
decreased, the column of mercury became shorter. 

Testing the "Sea of Air" 

Torricelli never checked the "sea of air" to see if it 
exerted less pressure at higher places than at the "bot- 
tom" of the "sea." It was the French scientist, philosopher, 
and mathematician Blaise Pascal who suggested a way 
to test Torricelli's basic idea. Pascal was not very healthy, 
so he asked his brother-in-law Florin Perrier to do the 
experiment. 

In 1 648 Perrier and several observers climbed a moun- 
tain, carrying a barometer with them. Another experi- 
menter stayed at the base of the mountain to keep track 
of another barometer there. 

At the base of the mountain both barometers read 28.2 
inches— that is, the top of the mercury in the tube was 

NATURE AND SCIENCE 



28.2 inches above the mercury in the dish. About halfway 
up the mountain, Perrier's barometer read 26.6 inches. 
At the top it read 24. 1 inches. When the climbers returned 
to the base of the mountain, their barometer again read 
28.2 inches. The experimenter who had stayed below 



PROJECT- 



With an aneroid barometer (see "Another Kind of 
Barometer"), you can easily test the "sea of air" 
idea the same way Perrier did in 1648. (An aneroid 
barometer usually costs $7.50 or more, but we found 
one in a discount store for only $4. Maybe there is a 
barometer in your school, or perhaps a friend has one 
in his house.) 

Carry an aneroid barometer up a high hill or moun- 
tain and see what happens to the air pressure as you 
go up and as you come down. Take an aneroid 
barometer with you when you go on an auto trip. 
What happens to the air pressure as you go up and 
down hills? What happens to the air pressure as you 
go up and down in an elevator? Can you detect any 
pressure change when you carry the barometer up or 
down a flight of stairs? How about several flights? 



reported that his barometer had read 28.2 inches through- 
out the day. 

The results of Pascal's experiment seemed to support 
Torricelli's idea that we live at the bottom of a "sea of air." 



(Can you explain why?) But it did not explain why the 
air pressure changes from day to day at the same place, 
as Torricelli had discovered with his barometer. After all, 
the water pressure at a particular depth in a lake or ocean 
does not change from day to day. 

This question was answered about 1660 by Robert 
Boyle, an English scientist who had succeeded in building 
a very good air pump. To test Torricelli's idea that a 
change in air pressure moves the mercury up or down in 
a barometer tube, Boyle made a large glass vessel to cover 
the bottom of a barometer (see diagram). When he 

(Continued on the next page) 



MERCURY 
BAROMETER — 



SEALED PLUG 



STOPCOCK 



AnotherVrKind of Barometer 





Can you figure out how 
Robert Boyle used this 
device to increase or de- 
crease the air pressure 
around the base of the 
barometer? 



VALVE 



PISTON 




LEVER 



Mercury barometers are still used by mefeoro/og/'srs (scientists who 
study and predict the weather). You may have seen another kind of 
barometer, though, called an aneroid barometer (see photo). You 
may have one in your house or at school. 

Air is free to enter this barometer through a hole in the back of 
its wood or metal case. Instead of pressing down on the surface of 
a pool of mercury, the air presses on the sides of a thin, round, hollow 
metal can (see diagram). Most of the air was removed from the can 
before it was sealed. 

The outside of the can is attached to a spring, and the end of 
the spring is connected by a series of levers to a chain that turns 
the pointer shaft. When the air pressure increases, the sides of the 
can are pressed inward and pull on the spring. This motion pulls 
tfie chair), turning the pointer so that it points to a higher number 
on the barometer dial. The dial is calibrated, or marked, to show 
the pressure in inches, tenths of inches, and hundredths of inches 
(the height the mercury would be in a mercury barometer). (Why 
does the scale only measure from 27.5 to 31.5 inches?) 

When the air pressure decreases, the walls of the can are pushed 
outward by the air in the can; the chain eases its pull on the pointer 
shaft, and a spring turns the pointer to a lower reading on the dial. 

An aneroid barometer is much smaller and easier to carry around 
than a mercury barometer. But changes in temperature affect its 
rpetal can more than they affect a column of mercury, so a mercury 
barometer measures the air pressure more accurately. 



science I7in;i;wi[i]q 



Discovering an "Ocean" (continued) 
pumped air into the vessel, the mercury rose, just as Tor- 
ricelli had said it would. When he pumped air out of the 
vessel, the mercury level dropped in the tube. 

Boyle discovered that, unlike water, air can be com- 
pressed) or "squeezed together," making the air more 
dense than before. He also discovered that the pressure 
exerted by air is proportional to the density of the air. This 
means that if you squeeze air into a container until the 
amount of air in it has been doubled, the outward "push" 
of the air will also be doubled. 

Boyle showed that the day-to-day changes in air pres- 
sure at a particular place, which Torricelli had discovered 
with his barometer, must be caused by changes in the 
density of the air at that place. Soon scientists began to 
realize that the movements of the air that we call "winds" 
are currents in our "sea of air" caused by dense air masses 
sinking toward the "bottom" and pushing less dense air 
masses out of their way. Torricelli had "discovered" a 
vast "new ocean" for scientists to explore ■ 



MAKE YOUR OWN BAROMETER 

On a seacoast like Cape Cod, Massachusetts, fisher- 
men and their families, hotel keepers, and vaca- 
tioners are especially concerned about changes in the 
weather. The Cape Cod barometer (see photo) is a 
simple and inexpensive instrument for detecting the 
changes in air pressure that usually bring a change 
in the weather. 

You can make a miniature Cape Cod barometer 
with a large test tube, a cork or rubber stopper, a 
short tube made of glass or stiff plastic, and a longer 
tube of clear, flexible plastic (see photo). Fill the 
test tube with water mixed with vegetable coloring 
before you push the stopper with the glass tube run- 
ning through it into place. 

What will happen to the level of the water in the 
flexible tube when the air pressure increases? When 
it decreases? Do you think the level of the water will 
be changed by changes in temperature as well as by 
changes in air pressure? Can you think of a way to 
find out? 



■ Cartoonists seem to like yeast. You may have se<ij 
cartoon that showed bread dough rising furiously, bxj 
ing out of an oven and creeping across a table like a h 
animal trapped in a shapeless sack. 

Yeast does cause bread dough to rise, but as you prq 
ably already know, it doesn't act as wildly as cartooni 
picture it. In a way, however, the cartoons are partly rig 
Yeast is alive. It is a one-celled plant. Yeast cells rep 
duce rapidly when they have proper growing conditio* 

When conditions are right, yeast cells react with the si 
stances they are mixed with and give off alcohol and a gj 
carbon dioxide. In baking bread, the yeast releases tj 
bubbles of carbon dioxide gas throughout the dough. Tha 
countless bubbles become trapped by the sticky fir 






These yeast cells, pho- 
tographed through a 
microscope, are magni- 
fied about 1200 times. 



G 




>v 



How do yeast cells react with 
different kinds of foods? 
Here is a simple investigation 
to help you discover how to . . 

by Nancy M. Thornton 




CAPE COD 
BAROMETER 



>ugh, causing the dough to grow in size and to become 
onge-like. When the bread bakes, the soft dough sur- 
unding these bubbles hardens. Heat causes the carbon 
oxide to escape into the air. The small amount of alcohol 
at is produced also disappears. 

ixing Yeast with Different Foods 

You can try some simple investigations to find out what 
hditions are best for the growth of yeast. It is hard to 
tect the alcohol given off by yeast without using special 
uipment. Carbon dioxide, however, causes a bubbly 
am that you will be able to see. 

First make a yeast-water solution. Add one tablespoon 
dry yeast to one cup of warm water. Stir thfe water until 
2 yeast dissolves. Then put about a tablespoon of this 
lution into each cup of an empty egg carton (or each 
p in tins used to bake cupcakes or mufntls). Number 
e cups frorh 1 to 12, and make a table Dri a sheet of 
!per, also numbered 1 to 12. (A sampie table is shown 




on this page.) Use the table to keep a record of what you 
do with each cup. 

Stir the contents of each cup, using a clean toothpick. 
After stirring, leave one cup alone. This will be a control, 
so that you will know how each cup of yeast solution 
would have acted without anything added to it. To each 
of the remaining cups, add about one-fourth of a teaspoon 
of one of the following: flour, cooking oil, syrup, milk, 
salt, white sugar, meat (cooked or uncooked; cut into small 
pieces), diet sweetener, powdered sugar, brown sugar, 
cornstarch. 

Stir each cup well, using a clean toothpick for each. Do 
you see any foaming of carbon dioxide gas right away? 

Put the carton in a warm place for 15 minutes. You can 
put it on a radiator or in an oven preheated to 150°. Then 
check to see if carbon dioxide gas is being given off. Put 
the carton back over the heat and check again in another 
10 minutes. Does the total time that the yeast solutions 
are heated make ariy difference in the amount of carbon 
dioxide foam that is produced? 

What kind of food reacted most with the yeast, as indi- 
cated by the amount of carbon dioxide foam produced? 
From these results, can you name an important ingredient 
in making bread? 

INVESTIGATIONS 

• How does sugar cdncentration affect the produc- 
tion df carbon dioxide? Using a clean egg carton and 
the same strength yeast solution, add white sugar 
td several cups. Put *4 teaspoon into one cup, y 2 



up to 2 teaspoons. Remember to have a control— a 
cup containing only water and yeast. Put the cups 
in a warm place and see which one produces the most 
carbon dioxide foam. 

• How does temperature affect the production of 
carbon dioxide? Put a tablespoon of yeast solution 
and Y4 teaspoon of white sugar into each of five 
separate containers. Put one cup in each of these 
places: a freezer, the refrigerator, a room at about 
70°F, an oven preheated to 150°, and an oven pre- 
heated to 300°. Observe each cup every five minutes 
for about 25 minutes. What temperature seems best 
for producing carbon dioxide? 




't'A> 



l. CONTROL 
(NOTHING ADDED) 



J 



WHAT'S 
NEW 

by Roger George 




An airport in a lake may soon be 
built near Chicago, where heavy air traf- 
fic is putting a strain on present airport 
facilities. Engineers would first erect a 
circular dam on the bottom of Lake 
Michigan. It Would be four miles across 
and would rise 18 to 24 feet above the 
surface. Then the water inside the dam 
would be pumped out to expose the hard 
clay bottom of the lake, where a landing 
field and terminals would be built. 

A tunnel, perhaps combined with a 
causeway, would span the 5}A miles be- 
tween the airport and downtown Chi- 
cago. The airport would be close to the 
city, yet not in a heavily populated area. 
Approaches would be clear, noise would 
be less bothersome, and the field could 
be expanded easily. 

Loud rock music in large doses can 
harm hearing, recent tests suggest. Ten 
Florida teen-agers, tested before and 
after a rock dance, all showed a tem- 
porary hearing loss at evening's end. A 
test of a young five-man combo in Texas 
revealed that one man had temporary 
hearing loss after playing, and three had 
already suffered some permanent loss. 

In a test made by Dr. David M. Lips- 
comb, director of audio clinical services 
at the University of Tennessee, in Knox- 
ville, a guinea pig was subjected to the 
listening habits of an average disco- 
theque-goer. After a total of 88'/2 hours 
of music as loud as the noise of a jet 
engine, many of the guinea pig's inner 
ear cells had been destroyed. And, notes 
Dr. Lipscomb, the music he played to 
the guinea pig was not so loud as the 
music he had heard in some of the noisier 
discotheques around Knoxville. 

16 



The strongest glue known to man 

may be the adhesive that barnacles use 
to stick themselves to rocks, wharves, 
ships, and even whales (see photo). The 

mats' : lr * **- * ^3 1 ' ^ " 



it** 



wW? 






5% 



A strong, quick-drying glue that they 
produce holds these barnacles to an 
aluminum plate that was used to collect 
them. Scientists are studying barnacles to 
see whether their glue can be used to 
hold fillings in teeth. 

glue is produced in liquid form by these 
small, hard-shelled sea animals. It flows 
out through their antennae and hardens 
after 15 minutes in the water. It sticks 
tightly to all surfaces — even slippery 
ones — and is extremely hard to dissolve. 
Scientists at the University of Akron, 
in Ohio, are studying barnacle glue for 
the National Institute of Dental Re- 
search. They think it may be ideal for 
gluing fillings into teeth. In filling teeth 
today, a dentist has to remove the decay 
and then drill a hole in the healthy part 
of the tooth to anchor the filling. Even 
so, many fillings eventually fall out. Bar- 
nacle glue might hold fillings in place 
longer — and without the need for drilling 
holes in healthy tissue. 

Walking catfish are causing con- 
cern in Florida. These fish, often two 
feet long, are at home both in water and 
out. On land they move along on short, 
thick fins. Breathing through special 
organs located just above their gills, they 
can stay out of water for several hours. 
The catfish sleep by day and hunt food 
by night. In captivity they've attacked 
and killed fish their own size. They've 
even snapped at dogs during overland 
trips, according to some reports. 

Originally from Asia, the walking cat- 
fish were introduced to the Fort Lauder- 
dale area several years ago by a fish 
farmer. They have now multiplied and 
are taking over ponds and waterways, 
replacing bass and other local fish. Ef- 
forts to reduce their numbers have failed 



so far. Poisoning a pond, for example, 
may not work if a fish can walk to the 
next one. 

An orbiting repairman may be 

able to fix disabled space satellites. The 
two-armed, three-legged robot would be 
attached to a small satellite and placed 
in orbit. Radio signals from the ground 
would send the robot from its "home" 
satellite to a disabled satellite. Television 
pictures transmitted by the robot would 
enable a man on the ground to operate 
it. After the robot had completed repairs 
or refueling, it would return to its own 
satellite to wait for the next distress 
signal. 

The General Electric Company, which 
is developing the robot, says it could be 
placed in orbit by the mid-1970s and 
could stay there four or five years. 

74 billion cans, bottles, and jars 

are produced in the United States each 
year. Many of these end up littering the 
landscape — a sorry sight and an expen- 
sive mess to clean up. 

Bottles or cans that dispose of them- 
selves may help solve this problem. A 
Swedish company has developed a con- 
tainer made of stiff plastic inside a paper 
sleeve. The container is strong enough 
to withstand shipping and storage. But 
when it is exposed to acids in the soil 
and to sunlight, the paper rots and the 
plastic disintegrates. In South Carolina, 
a self-destroying bottle is being devel- 
oped by Dr. Samuel F. Hulbert, a 
ceramics professor at Clemson Univer- 
sity. When this bottle is broken, the 
pieces will mix with the water in the air 
and melt away. 



If food producers begin using the dis- 
appearing cans, bottles, and jars now be- 
ing developed, our litter heaps may some- 
day look like this. 

NATURE AND SCIENCE 



Using This Issue . . . 

(continued from page 2T) 

in "pounds per square inch"? In pre- 
dicting the weather, it is more impor- 
tant to know whether the pressure is 
going up or down, and how rapidly, 
than to know the exact pressure. Engi- 
neers need to know the average air 
pressure at different altitudes. For ex- 
ample, the air pressure inside a high- 
flying airplane is kept about the same 
as at sea level, so the body of the 
plane must be made strong enough to 
keep it from bursting open when it is 
flying in air at much lower pressure. 

Answers to Questions in the Article 

• Why can't most lift pumps lift 
water farther than 30 feet at best? 
(Page 11.) The piston must be loose 
enough to move in the chamber, so a 
little air seeps by it, back into the 
lower part of the pump chamber. Also, 
some of the atmosphere's "push" is 
used up in overcoming cohesion (the 
tendency of water to stick together) 
and adhesion (the tendency of water 

! to cling to the walls of a pipe). (See 

Y'Climbing Water," N&S, Sept. 16, 

\l968.) 

Water could be pumped out of a 
deep mine by placing lift pumps at dif- 
ferent levels so none had to lift water 

(farther than 28 feet or so. 

It usually takes several "pumps" of 

;the lift pump handle to get most of the 
air out of the pump chamber. 

• Why does water weigh less the 
farther it is from the center of the 
I earth? (Page 12.) The pull of the 
learth's gravity on an object deter- 
' mines its weight, and this pull is weak- 
!er the farther the object is from the 
jearth's center of mass (see N&S, Nov. 

13, 1967, page 2T). 

• How did Torricelli figure out that 
a lift pump should be able to lift mer- 
fury only about 30 inches? (Page 12.) 
He divided 408 inches (34 feet) by 
[13.5 (the number of times mercury is 
; heavier than water). 

Activities 

• Have your pupils punch three nail 
holes in the side of a tall fruit juice 
can, near the top, near the bottom, and 
halfway down. Hold the can over a 
sink and fill it with water. The dis- 

November 11, 1968 



tance the water is pushed out of the 
holes shows that pressure increases 
with depth in a liquid. 

If you have an aneroid barometer, 
place it in a clear plastic bag (without 
holes!) and seal the top with a tie 
band, string, or tape. Have your pupils 
move it slowly up and down in a tank 
of water and observe how the pressure 
changes (see photo). 

• Place an aneroid barometer in a 
plastic bag and seal it as above, but 




To demonstrate increase of pressure with 
depth in a liquid, seal an aneroid barom- 
eter in a clear plastic bag and move it 
slowly up and down in a tank of water. 

without squeezing the air out of the 
bag. Let your pupils squeeze the bag 
and explain what happens to the ba- 
rometer needle. 

• Have your pupils make a simple 
barometer by stretching a piece of rub- 
ber from a balloon over the top of an 
empty glass milk bottle, fastening it 
with a rubber band, and gluing a soda 
straw to the center of the rubber. Cut 
the end of the straw to a point and use 
a ruler as a scale (see diagram). Have 
your pupils test this barometer near 
(but not over) a warm register or radi- 
ator to see how it is affected by changes 
in temperature. Is it more sensitive to 
heat than an aneroid barometer? Less? 
How about a Cape Cod barometer? 
Have your pupils think about which 
expands faster when heated — air, 
water, or mercury. 

• You might have an interested 
pupil find out about Otto von Guericke 
and the Magdeburg hemispheres, and 
test the experiment with two suction 
cups (the kind used by plumbers to 



clear drainpipes, or even the kind 
used to hold some plastic coat hooks 
to a wall). 

Brain-Boosters 

Mystery photo. The photo, showing 
a portion of a chain-link fence covered 
with snow, has been printed upside 
down. Turn it right-side up and you 
can see some trees through the open 
spaces of the fence. 

What would happen if? Fill a paper 
cup and two tin cans with hot water to 
the levels shown, put an inexpensive 
thermometer in each, and let a pupil 
record the temperatures every 1 5 
minutes. 

Since metal is a better conductor of 
heat than is paper, and since a small 
volume of water drops in temperature 
faster than a large one, the can half 
full of water will show the fastest cool- 
ing. (Both cans of water lose heat at 
about the same rate; but because the 
full can contains twice as much water 
as the half-full can, it has twice as 
much heat to lose when both cans are 
at the same temperature. So the tem- 
perature of the full can drops about 
half as fast as that of the half-full can.) 

With several identical cans filled to 
the same level with various liquids, 
you and your pupils can determine the 
relative cooling rates of the liquids. 
Heat the liquids uniformly by placing 
the cans on a radiator or in a pan of 
very hot water; then measure their 
temperature drops every quarter hour. 
Of course, the liquids that lose heat 
slowest will also gain heat slowest, so 
you must allow sufficient time for all 
the liquids to reach the same tempera- 
ture before beginning your readings. 

Some liquids you could test would 
(Continued on the next page) 



cardboard 



rubber 

from 

balloon 



straw — 



tape 




3T 



Using This Issue . . . 

(continued from page 3T) 

be alcohol, milk, oil, liquid soap, and 
syrup. One of the pupils could draw 
up a simple graph showing the rela- 
tive rates at which the liquids lose 
their heat. 

Can you do it? Let your students 
pop a few fully inflated balloons with 
a pin and count the number of pieces 
into which each one breaks. If a bal- 
loon is only partly inflated, it will often 
remain in one piece after a pin-prick. 
Another way to make the balloon stay 
in one piece after being punctured is to 
fill it with water. 

The children can also find out what 
happens when they break a balloon in 
other ways— by over-inflating it, for 
example, or by sitting on it. 

Fun with numbers and shapes. Here 
is one solution to the addition prob- 
lem: 2348 There could conceivably 
2348 be others. Some pupils 
2348 may enjoy devising sim- 
2348 ilar problems for their 
9392 classmates to solve. 

For science experts only. Of course, 
neither ice nor anything else is ever 
completely frictionless. But if you did 
find yourself stranded on frictionless 
ice, you could get off by utilizing New- 
ton's Third Law of Motion: For every 
action, there is an equal and opposite 
reaction. Blowing, or throwing an ob- 
ject away from you, would thrust your 
body in the direction opposite to the 
blow or throw. 

For more information on Newton's 
Third Law., and related investigations, 
see "The 'Law' of Pushing," N&S, 
Feb. 5, 1968. 

Just for fun. You can do this dem- 
onstration in the classroom with an 
aquarium tank, using about half the 
amounts of baking soda and vinegar. 
Since carbon dioxide is a fairly dense 
gas, it does not rise and the bubbles 
do not fall through it. 

You can make the carbon dioxide 
layer visible by dropping a burning 
paper towel into the tank; the smoke 
will become mixed with the gas. If you 
rock the tank back and forth, your 
pupils can see the smoky carbon di- 
oxide sloshing back and forth like 
water. 




Prepared under the 
supervision of The 
American Museum 
of Natural History 



wall charts 

Srom 
nature and science 



Let your classroom walls help you teach with a completely new set of 10 Na- 
ture and Science Wall Charts. Reproduced from the pages of Nature and 
Science— and enlarged 300% in area— these Wall Charts cover a range of sub- 
jects that your science class should know about. 

For chalkboard, bulletin board, wall— for science exhibitions and displays— 
here are lasting sources of information that are always ready to catch (and 
educate) the wandering eye of any student. 



* all fully illustrated in vivid color 

* printed on durable, quality stock 

* each chart an abundant 22 by 34 inches 

* delivered in mailing tube for protection and storage 



Six Ways to Success — describes six 
ways in which plants and animals are 
adapted to insure survival of the species. 

Travel Guide to the Sun and Its Planets 

— depicts our solar system,showing rel- 
ative sizes of the planets, number of 
satellites, temperature, diameter, dis- 
tance from sun. 

The "Spirit" That Moves Things — ex- 
plains what energy is, where it comes 
from, and how it can change form. 

History in the Rocks — cross section of 
Grand Canyon shows how each geo- 
logical stratum was formed and illus- 
trates some representative fossils from 
each period. 

Spreading the Word — depicts how man 
has communicated information from 
one place to another through the ages. 



Visit to a Plant Factory — shows how 
green plants make their own food and 
how the food is transported to their 
parts. 

Rabbit Rollercoaster — illustrates the 
annual population cycle of the cotton- 
tail and describes why few rabbits live 
as long as a year. 

How Diseases Get Around — diagrams 
ways in which diseases are spread and 
shows how vaccines protect against 
disease. 

Who Eats Whom — explains the ecol- 
ogy of the sea and some of the links in 
its "food chains." 

The Horse's First 55 Million Years- 
museum reconstructions in a time-line 
presentation illustrate the evolution of 
the horse. 



Imagine your pupils' excitement as you display a different chart each month 
of the school year. Order a complete collection of ten for only $7.50. 

To order, use postpaid order form bound into this issue. 



4T 



NATURE I \/> .« II \< I 



nature and science 

TEACHER'S EDITION 

VOL 6 NO. 6 / DECEMBER 2, 1968 / SECTION 1 OF TWO SECTIONS 

COPYRIGHT © 1968 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 



nature 

and science 



4 N & S REVIEWS ► 

Books That Will Help 
You Teach Science 

by Dulcie I. Blume 

This is the first of several reviews of some books published in the past five 
years that have earned a front-row position on the shelves of elementary 
school teachers of science. Many were written by people with years of ex- 
perience in teaching science to children. All of these books will help you to 
answer questions . . . to develop and direct investigative activities . . . to create 
classroom situations from which your pupils will be propelled to their own 
investigations, observations, and books. 



Nature in the City, by John Rublow- 
sky (Basic Books, 1967, 152 pp., $4.95). 
More than a few of us live and teach in 
urban communities, yet do we see the 
nature there? Did you know that the fox, 
the coyote, or the opossum live in the 
city? 

"Not many people come to the city to 
study nature," begins the author; "yet 
this is exactly what we are going to do." 
He then gives us an introduction to the 
ecology and natural history of the city, 
discussing birds, beasts, insects, trees, and 
the sometimes ruthless, sometimes pleas- 
ant relationships between man and the 
other animals and plants he displaces. In 
addition to an account of the plant and 
animal life of the city today, there is a 
brief history of living things in cities, tell- 
ing the changes that have occurred from 
pre-Colonial days until now. 

Experiences and Demonstrations in 
Elementary Physical Science, by Richard 
F. Thaw and John E. Morlan (Wm. C. 
Brown Company, 1964, 187 pp., $4.50). 
A whole book of experiments — one to a 
page and each well illustrated. The ex- 
periments are grouped under 12 head- 
ings: light, astronomy, sound, chemistry, 
geology, magnetism, electricity, gravity 
and flotation, air, heat, weather, and aero- 
space study. 

Mrs. Dulcie I. Blume is Coordinator of Cur- 
riculum Materials of the Alameda County 
School Department, Hayward, California. 



The book is organized around specific 
problems dealing with basic principles of 
science, but the various concepts are not 
presented in a definite sequential order. 
A problem is presented and materials 
needed to find a solution are listed. Step- 
by-step, fully illustrated directions are 
given to ensure successful completion of 
each activity. Because emphasis is placed 
on simplicity and directness, the book 
tends to increase confidence in the teach- 
ing of science. 

In addition to the experiences and 
demonstrations, the authors present 13 
bulletin board designs that can provide 
for motivation and student involvement, 
and can present useful scientific informa- 
tion in an artistic manner. 

Teaching Science through Discovery, 

by Arthur Carin and Robert- B. Sund 
(Charles E. Merrill Books, 1964, 514 pp., 
$1 1.35). This is a book for those of you 
who would like to try teaching science 
through the discovery method, or who 
would like to become more skilled in the 
method. The first three parts of the book 
can help to build an appreciation and 
understanding of a modern science edu- 
cation program in the elementary school. 
Part 4 (more than half the book) will 
probably be the section that you will 
appreciate most. Entitled "Discovery 
Lesson Plans and Other Activities for 
Teaching Science," it contains elemen- 
tary science experiences and lesson plans, 
(Continued on page 4T) 



IN THIS ISSUE 

(For classroom use of articles pre- 
ceded by •, see pages 2T and ST.) 

Exploring Drops and Splashes 

Your pupils can investigate how 
falling water drops interact with dif- 
ferent surfaces and erode soil and 
rock. 

"Treasures" in a Ton of Dirt 

By sifting gravel from ancient ant 
hills, young people are helping sci- 
entists find rare fossils. 

Ladders for the Leapers 

Man-made dams block salmon from 
their upstream spawning grounds. 
Here is how scientists are trying to 
help the fish get over the dams. 

• Brain-Boosters 

• The Physics of Fasteners 

Showing how fasteners work, this 
Wall Chart should whet your 
pupils' curiosity about other com- 
mon "tools." 

How Fast Do Your Fingernails 
Grow? 

• Can the Elm Be Saved? 

How the Dutch elm disease is 
spread, and what scientists have 
learned so far in trying to control it. 

• The Moving Story of Osmosis 

A Science Workshop: investigat- 
ing how water passes through mem- 
branes. 

IN THE NEXT ISSUE 

The mystery of the Easter Island 
monuments . . . Why does a sea turtle 

lay about 100 eggs? Science 

Workshops in radio signal trans- 
mission and how plants are affected 
by light. 



USING THIS 

ISSUE OF 

NATURE AND SCIENCE 

IN YOUR 

CLASSROOM 



Physics of Fasteners 

There are so many different kinds of 
fasteners that your pupils may keep 
discovering them all year long. They 
can be classified in many different 
ways— a good exercise in scientific ob- 
servation and thinking. 

Suggestions for Classroom Use 

Before your pupils see the chart, you 
might ask them to think of as many 
different kinds of "fasteners" as they 
can— things that hold other things to- 
gether. Mention paperclips, glue, and 
nails as a starter. Ask about fasteners 
on their clothes: buttons and button- 
holes, hooks and eyes, snaps, zippers, 
belts, buckles, stitches, shoelaces, and 
—in shoes— cement and nails. In the 
classroom: clips, clamps, staples, 
thumbtacks, rubber bands, string, 
nails, screws, bolts and nuts, rivets, 
glue, paste, containers of all kinds, 
locks, ringbinders, stitches (in books), 
and so on. Can they think of other 



NATURE AND SCIENCE is published for The American 
Museum of Natural History by The Natural History 
Press, a division of Doubleday & Company, Inc., fort- 
nightly September, October, December through March; 
monthly November, April, May, July (special issue). 
Second Class postage paid at Garden City, N.Y. and at 
additional office. Copyright « 1968 The American 
Museum of Natural History. All Rights Reserved. Printed 
in U.S.A. Editorial Office: The American Museum of 
Natural History, Central Park West at 79th Street, 
New York, N.Y. 10024. 

SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester 
per pupil, $1.95 per school year (16 issues) in quanti- 
ties of 10 or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's 
edition $5.50 per school year. Single subscription per 
calendar year (17 issues) $3.75, two years $6. Single 
copy 30 cents. In CANADA $1.25 per semester per 
pupil, $2.15 per school year in quantities of 10 or more 
subscriptions to the same address. Teacher's Edition 
$6.30 per school year. Single subscriptions per cal- 
endar year $4.25, two years $7. ADDRESS SUBSCRIP- 
TION correspondence to: NATURE AND SCIENCE, The 
Natural History Press, Garden City, N.Y. 11530. Send 
notice of undelivered copies on Form 3579 to: NATURE 
AND SCIENCE, The Natural History Press, Garden City, 
N.Y. 11530. 



fasteners in their homes, or outdoors? 

When you have a list of 20 or so 
fasteners, have your pupils think of 
ways to classify, or "group" them. 
Here are some possible ways: (1) by 
the materials the fasteners are made of; 
(2) by the kinds of materials they 
usually hold together; (3) by whether 
or not they allow the fastened objects 
to move in one or more directions; 
(4) by whether they are easy or hard 
to unfasten; (5) by whether they are 
designed for temporary or "perma- 
nent" fastening; (6) by the kinds of 
force they have to withstand (pull, 
push, bend, stretch, squeeze, impact, 
slide, and so on); (7) by the kinds 
of wear they have to withstand (rub- 
bing, weathering, rotting, heat, cold, 
and so on); (8) by whether or not 
they have to be fastened to objects 
with other kinds of fasteners (locks 
do, screws don't). Your pupils may 
even think of other ways to classify 
fasteners. 

Have them look especially for sim- 
ilarities in the way certain fasteners 
work. Paperclips, spring clips, and 
rubber bands all "squeeze" objects to- 
gether; adhesives "stick" things to- 
gether. But what do nails do? Why 
does a buttoned button hold two pieces 
of cloth together? Does a zipper work 
anything like a snap fastener? (Both 
are blocking spring fasteners.) 

• Here are answers to some of the 
questions posed in the chart: A nail 
holds two boards together by blocking 
them from sliding apart... A wedge 
holds a door fast by "pushing" the door 
and floor apart as well as by "block- 
ing" the door. . ."Suction discs" are 
held to a smooth surface by atmo- 
spheric pressure when the air is 
squeezed out from between the disc 
and the surface. 

An adhesive usually works better on 
smooth surfaces that can be fitted to- 
gether with a thin, even coating of 
adhesive between them. (Rough sur- 
faces cause an uneven layer of ad- 
hesive; where the adhesive is thick 
the bond may be weaker than where 
most of the molecules in the coating 
are in contact with molecules of the 
bonded surfaces.) 

Water forms a surprisingly strong 
adhesive bond between sheets of glass. 



(Have your pupils test this by lifting 
one microscope slide off another slide 
without sliding it sideways, then doing 
the same thing with a layer of water 
between the slides.) 

Plastic bags are often sealed closed 
with heat (welding) ... If the cohesion 
of glue is weaker than its adhesion to, 
say, wood, the glue itself might be 
pulled apart. 

• The discussion of how matter is 
"fastened" together by electrical (and 
other) forces is limited by space, but 
it should convince your pupils that 
fasteners are important. You might 
emphasize that while an electric cur- 
rent can produce magnetic force (see 
"Electricity from Magnets," N&S, 
March 18, 1968), the attraction be- 
tween unlike charges of electricity is 
not the same force as the attraction be- 
tween opposite poles of two magnets. 

• Can your pupils think of some 
"fasteners" that occur in nature and 
explain how they work? Containers, 
such as cell membranes (see page 15), I 
seed pods, nests, cocoons, and skin, 
hold things together by blocking their 
movement. So do plant roots and 
spider silk and the hooks on plant 
burrs, climbing vines, and animal 
claws. Barnacle glue and spider silk 
are adhesives, and so is the "cement" 
(often hardened clay) that holds small 
rocks and pebbles together to make 
conglomerate rock. An animal skele- 
ton has many interesting joints that 
fasten bones together while permitting 
them to move. A few animals— the 
octopus for one— have "suction dises" 
to hold them to solid objects or their 
prey. 

Can the Elm Be Saved? 

The Dutch elm disease offers an ex- 
ample of the troubles that result when 
an organism is moved from one envi- 
ronment to a new one where it has few 
or no natural enemies. (For more in- 
formation on this subject, see "The 
Animal Movers," N&S, Oct. 2, 1967.) 
The fungus disease is more of a prob- 
lem in North America than in Eu- 
rope, where the bark beetles that help 
spread the disease arc kept in cheek 
by a wasp that kills up to 70 per cent 
(Continued on page 3T) 



2T 



SATURI I V/> vr // \CE 



VOL. 6 NO. 6 / DECEMBER 2, 1968 



ind science 



How do paperclips, boxes, 
nails, glue, and electricity 
hold things together? 

see page 8 

THE PHYSICS 
OF FASTENERS 



CAN YOU GUESS 

HOW MILK GOT 

THIS WAY? 

see page 2 







SCIENCE 



nature and science 

VOL. 6 NO. 6 / DECEMBER 2, 1968 

CONTENTS 

2 Exploring Drops and Splashes, by Robert Gardner 

4 "Treasures" in a Ton of Dirt 

5 Ladders for the Leapers, by Susan J. Wernert 

7 Brain-Boosters, by David Webster 

8 The Physics of Fasteners 

1 How Fast Do Your Fingernails Grow? 

1 1 Can the Elm Be Saved?, by Dave Mech 

14 What's New?, by B. J. Menges 

1 5 The Moving Story of Osmosis, 

by Nancy M. Thornton 

PICTURE CREDITS: Cover, p. 2, H. E. Edgerton; p. 3, Soil Conservation 
Service, U. S. Department of Agriculture; p. 4, Yale University News Bureau; 

C. 5, photo from U. S. Army Corps of Engineers; pp. 3, 5-9, 12, 16, drawings 
y Graphic Arts Department, The American Museum of Natural History; p. 6, 
Bureau of Commercial Fisheries; p. 7, photo from Education Development 
Center; p. 10, AMNH; p. 11, (left) George Porter, (right) John H. Gerard, both 
from National Audubon Society; p. 13, Henry Mayer, from National Audubon 
Society; p. 14 (top) Lincoln P. Brower, from Science, (bottom) Goodyear Aero- 
space Corporation. 



PUBLISHED FOR 

THE AMERICAN MUSEUM OF NATURAL HISTORY 

BY THE NATURAL HISTORY PRESS 

A DIVISION OF DOUBLEDAY & COMPANY, INC. 

editor-in-chief Franklyn K. Lauden; executive editor Laurence P. 
Pringle; associate editor R. J. Lefkowitz; assistant editors Mar- 
garet E. Bailey, Susan J. Wernert; editorial assistant Alison New- 
house; art director Joseph M. Sedacca; associate art director 
Donald B. Clausen • consulting editor Roy A. Gallant 

publisher James K. Page, Jr.; circulation director J. D. Broderick 
promotion director Elizabeth Connor 
subscription service Frank Burkholder 

NATIONAL BOARD OF EDITORS 

PAUL F. BRANDWEIN, CHAIRMAN, Dir. of Research, Center for Study of 
instruction in the Sciences and Social Sciences, Harcourt, Brace & World. Inc. 
J. MYRON ATKIN, Co-Dir., Elementary-School Science Project, University of 
Illinois. THOMAS G. AYLESWORTH. Editor, Books for Young Readers, 
Doubleday & Company, Inc. DONALD BARR, Headmaster, The Dalton 
Schools, New York City. RAYMOND E. BARRETT, Dir. of Education, Oregon 
Museum of Science and Industry. MARY BLATT HARBECK, Science Teach- 
ing Center, University of Maryland. ELIZABETH HONE, Prof, of Education, 
San Fernando (Calif.) State College. GERARD PIEL, Publisher, Scientific 
American. SAMUEL SCHENBERG. Dir. of Science, New York City Board of 
Education. WILLIAM P. SCHREINER, Coord, of Science, Parma (Ohio) City 
Schools. VIRGINIA SORENSON, Elementary Science Consultant, Dallas In- 
dependent School System. DAVID WEBSTER, Staff Teacher, Elementary 
Science Study, Educational Development Center. Newton. Mass. • REPRE- 
SENTING THE AMERICAN MUSEUM OF NATURAL HISTORY: FRANK- 
LYN M. BRANLEY, Chmn., The American Museum-Hayden Planetarium. 
RICHARD S. CASEBEER, Chmn., Dept. of Education. THOMAS D. NICH- 
OLSON, Asst. Dir., AMNH. GORDON R. REEKIE, Chmn., Dept. of Exhibi- 
tion and Graphic Arts. DONN E. ROSEN, Chmn., Dept. of Ichthyology. 
HARRY L. SHAPIRO, Curator of Physical Anthropology. 

NATURE AND SCIENCE is published for The American Museum of Natural History by 
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What happens when a drop of water strikes* 

the surface of a puddle, a sidewalk, 

or the soil? With a medicine 

dropper, try— 



Exploring 
Drops and 

SPLASHES 



by Robert Gardner 



These photos were taken at high speed just after a wa 
drop fell into milk. The splash changed from a "crater" to] 
"jet" that broke up into drops shooting upward. Can you s< 
where the cover photo fits into this series? 






* 





You have probably watched raindrops as they strike a 
iewalk, pond, or puddle. But have you ever looked 
>sely to see what happens when a raindrop makes its 
iding? 

The photographs at left show what happens when a 
Dp of water strikes and enters a body of milk. If you try 
see this happening by letting drops fall from a medicine 
Dpper into a glass of water, you won't be able to see all 
: details, because everything happens so quickly. But 
/ou watch carefully you can see a "jet," like the one in 
: photographs, rise out of the water after the drop hits. 
>w far must the drop fall through the air before it pro- 
ces a "jet"? (To make the drops easier to see in all your 
Deriments, you can color the water with a few drops of 
)d coloring.) 

lard" Landings 

What happens if the drops fall onto a sheet of paper 
ting on a flat surface? Let the drops fall from different 
ghts— Vi inch, 1 inch, 6 inches, 1 foot, 2 feet, 3 feet, 
1 so on. Does the pattern made by the "splashed drop" 
inge as the height changes? What happens if the drop 
noving sideways when you drop it? (See diagram.) 



sure to try waxed paper. It repels water and makes the 
drop pattern quite different from the one ordinary paper 
makes. Can you guess what it will look like? 




What will the "splashed drop" pattern look like if the 
drops fall on a piece of paper that is inclined, or tilted, in- 
stead of lying flat? To find out, tape a sheet of paper to a 
piece of cardboard. Place one end of the cardboard on 
some books or blocks (see diagram). Can you guess what 
will happen to the pattern if you make the incline steeper? 
Less steep? ■ 




a you guess what the splash pattern will look like when 
i increase the speed? ( It may be useful to have a num- 
of paper sheets laid end to end when you try this 
)eriment. Why?) 

Suppose you let the drops fall onto different surfaces. 
11 this change the "splashed drop" pattern? You could 
wood, concrete, dirt, aluminum foil, and so on. Be 



PROJECT 



CATCHING RAINDROPS 

Next time it rains, cover a piece of cardboard or a 
cookie pan with waxed paper and catch some rain- 
drops. How big are the raindrops? Are they always 
the same size? 

Why is it easier to measure the size of a raindrop 
on waxed paper than on ordinary paper? Could 
you use ordinary paper to measure the size of rain- 
drops? 




The photograph above shows 
what happens when raindrops 
fall on a steep dirt-covered 
slope. Over many centuries 
whole mountains may be 
stripped of their soil by rain- 
drops. What could be done to 
prevent this kind of erosion? 



****»- 



.«*»VV 



Why do farmers plow around 
hills, as shown in this photo, 
ratherthan up and down them? 




December 2, 1968 



Treasures'* 

in aTon of 

Dirt 



■ More than a ton of gravel had been stored in the base- 
ment of the Peabody Museum of Natural History for over 
70 years. The gravel had been sent from Wyoming to the 
museum in New Haven, Connecticut, back in 1892. Scien- 
tists suspected that it contained some fossils, the remains 
of ancient life. 

The gravel had been piled up long ago by ants that were 
digging underground. Along with the gravel, these ants 
brought up many small bones and teeth. Paleontologists, 
the scientists who study ancient life on earth, have often 
found many small fossil "treasures" in ancient ant hills. 

Last summer, 50 New Haven children helped scientists 
search through some of the gravel. They discovered more 
than 30,000 fossils from animals that lived about 75 mil- 
lion years ago, at the very end of the "Age of Dinosaurs." 
They found teeth from all the varieties of dinosaurs of 
that time— horned dinosaurs, armored dinosaurs, plant- 
eating dinosaurs, meat-eating dinosaurs. 

The Hunt for Tiny Fossils 

But huge creatures like the 50-foot-long Tyrannosaurus 
were not the only creatures living 75 million years ago. 
There were many small animals, whose bones are often 
not noticed by fossil-hunters. Many fossils from these 
smaller animals were found by the boys and girls. They 
discovered fossils of fish similar to sturgeon and garpike. 



They found remains of reptiles other than dinosaurs— 
crocodile-like ones, lizard-like ones, turtle-like ones. There 
were parts from an animal like the opossum, and from a 
rat-like mammal that has no living relatives. 

But it was a fossil from a bird that stirred the most ex- 
citement. Fossils from ancient birds are rare, because the 
bones of birds are light, hollow, and easily broken. Often 
they do not remain whole long enough to become fossils 
'(see "How the Fossils Formed," on this page). Yet a 12- 
year-old girl discovered a claw (see photo) from a meat- 
eating bird like an owl or eagle. It is the oldest fossil of a 
meat-eating bird yet discovered— 25 million years older 
than the fossil that formerly held that record. 

The children in the summer program at the Peabody 
Museum of Natural History looked through just a small 
part of the gravel. Some of the children have continued 
the search in their spare time. Mrs. Kathryn Walton, as- 
sistant to the director of the museum, and Mr. Robert 
Bakker, director of the fossil hunt, report that there's still 
almost a ton of gravel left. Perhaps more fossil treasures 
will be found by other boys and girls when they continue 
the search next summer ■ 



HOW THE FOSSILS FORMED 

The fossils that the New Haven children discovered 
were not like the bones and teeth of animals that have 
just died. Even these hard parts are usually worn 
away as time passes. But sometimes they soak up 
water that contains minerals from nearby rocks. 
Gradually, small open spaces in the bones and teeth 
become filled with the minerals that seeped in with 
the water. The minerals might include silica if the 
nearby rocks were made of sandstone, or agate if 
they contained quartz. These minerals make fossils 
that are harder than the original bones and teeth. 



Some of the New Haven chil- 
dren search through the 
gravel. The photo below shows 
the claw they discovered, the 
oldest fossil from a meat-eat- 
ing bird ever found. Compare 
its size to the rule, numbered 
in inches. 



.**? 











How can a fish swim 
upstream when its 
way is blocked by 
a huge concrete dam 
An unusual laboratory 
is now testing... 

UDDERS 



by Susan J. Wernert 




w 



mm 




■ There's enough concrete in the Grand Coulee Dam, in 
the state of Washington, to build a six-lane highway around 
the border of the United States. The huge dam stores 
water from melting snow, and the water is used to produce 
electric power and to irrigate farmlands. But to a salmon 
trying to swim up the Columbia River to spawn, or lay its 
eggs, a dam like this one is just a gigantic roadblock. 

Most kinds (species) of salmon live in the oceans, but 
they spawn in fresh water. After the eggs have hatched, the 
young fish travel out into the sea— sometimes as far as 
2,500 miles from where they were born. After several 
years in the ocean, they swim back to their birthplaces. 
Each fish recognizes its own rivers and streams in a way 
that is not completely understood. Once "home," the fish 
reproduce and then usually die. If they do not reach their 
spawning grounds, they usually will not reproduce. 

Each year, the upstream salmon "runs" take place. And 
each year, the runs on many North American and Euro- 
pean rivers get smaller and smaller. This is the result of 
over-fishing for salmon, of pollution that kills salmon in 
the rivers, and of dams that keep the salmon from reach- 
ing their spawning grounds. 

How Fish Climb Ladders 

The name salmon comes from the Latin word for 
"leap," and the highest salmon jump is said to be 1 1 feet, 
4 inches. But the Grand Coulee Dam is 550 feet high. Men 
have to help salmon over the dams that lie between the 
sea and the spawning grounds. 

December 2, 1968 



The salmon are helped over some dams by use of special 
"fish ladders," like those at the Bonneville Dam, on the 
Columbia River at the Washington-Oregon border (see 
photo). Each watery "step" on these man-made ladders 



When the United States was still a British colony, ser- 
vants in New England were sometimes fed so much 
salmon that they refused to work unless they were 
given different food. Salmon was then plentiful and 
inexpensive, but the situation today is very different. 
The number of Atlantic salmon is dropping so quickly 
that soon there may be none left. 



is one foot high. The fish— salmon, steelhead trout, shad, 
and others— swim 16 feet between steps. In this way, they 
climb the dam gradually. But they don't jump into the air 
while going from step to step, as many disappointed tour- 
ists have discovered. It is possible for the fish to swim up 
the entire ladder without coming to the surface at all. 

To find out which sizes and shapes of ladders are best for 
fish, scientists working for the United States Army Corps 
of Engineers have set up a fish-ladder laboratory in a 
wooden building at the Bonneville Dam. Fish swimming 
up the dam's north ladder are guided into a passageway. 
The only way out is up the ladders in the laboratory (see 
diagram on next page). When the testing is finished, the 
fish leave by a passageway running to the north ladder 
over the dam. They usually are not handled by humans 
during the testing. (Continued on the next page) 



Ladders for the Leapers (continued) 



VIEW OF FISH LADDER LAB FROM ABOVE 



FISH LEAVE LAB 

HERE AND RETURN 

TO MAIN LADDER 



TO TOP OF DAM 



LADDER LABORATORY 



FISH "WAITING ROOM' 




c- 



I I I I I I I 



I I I 



LNTRANC 



f^F 




FISH CLIMB NORTH LADDER 
OF BONNEVILLE DAM 



Inside the lab, wooden steps of different heights, lengths, 
and widths can be put together to form a variety of ladders. 
Scientists can then figure out which ladders are best by 
measuring the time that the fish take in climbing and the 
energy that they use for climbing. A good ladder is one 
that the fish can climb quickly and easily. Most Pacific 
salmon do not eat during the entire trip from sea to spawn- 
ing ground. All of their energy comes from what was stored 
in their bodies. If they use up too much time or too much 
energy in ladder-climbing, they may never reach their 
spawning grounds to reproduce. 

The Endless Fishway 

To find out how much energy different kinds of fish 
use in climbing, the scientists use the laboratory's endless 
fishway (see photo). Here a fish climbs 1 6 steps arranged 
so that the lowest and highest steps are near each other. 
When the fish has reached the highest step, a gate drops 
behind it, and water is quickly let out of the step to bring 
the fish down below the lowest step of the fishway. The 
gate to the lowest step then opens, and the fish starts all 
over again. One sockeye salmon climbed for five days and 
five nights in this endless fishway, and his health was still 
good when scientists stopped the experiment! 

Results from the Bonneville laboratory show that the 
fish need ladders only half as wide as many now in use, 
and that the ladders can be much steeper. If the designers 
of new ladders use these findings, the fish ladders can be 
built at lower cost. 

But work at the fish-ladder laboratory is by no means 
ended. One of the best features of the laboratory is that a 
variety of problems can be studied. Wastes from indus- 
trial plants may raise the temperature of the Columbia 
River, and scientists at the Bonneville Dam are now in- 
vestigating how this heat pollution affects the climbing 



behavior of the fish. When they know how the fish are af- 
fected, they may be able to suggest what can be done 
about it. Those suggestions may help the salmon survive 
yet another problem caused by man ■ 




Workers build the endless fishway. A fish travels in the direc- 
tion of the arrow. When it reaches the highest step (shown 
in color), the fish is brought down below the next step so 
that it can continue climbing. 



NATURE AND SCIENCE 




HAVE YOU AN IDEA FOR A BRAIN-BOOSTER? 

Send it with the solution to David Webster, R.F.D. #2, 
Lincoln, Massachusetts. If we print it, we will pay you 
$5. Be sure to send your name and address. If several 
readers submit the same idea, the one that is most 
clearly presented will be selected. Ideas will not t)e re- 
turned or acknowledged. 



prepared by DAVID WEBSTER 




WHAT WILL HAPPEN IF? 

If you pour different 
amounts of water into two 
bottles of the same size 
and shape, then tap each 
bottle with a pencil, which 
bottle will make the higher 
sound? 



CAN YOU DO IT? 

Can you make a glass of water that contains just one eighth 
of a drop of milk? 




MYSTERY PHOTO 

Can you guess what is in this jar? 



FOR SCIENCE EXPERTS ONLY 

A man in Massachusetts placed a pan of old engine 
oil behind his garage. A few months later, 
in December, he looked in the pan and found 
it filjed with ice. Can you explain 
how this happened? 



FUN WITH NUMBERS AND SHAPES 

Suppose you keep your socks in a drawer that is the fourth 
from the top and the third from the bottom. How many draw- 
ers are there in the chest? 

Submitted by Andrea Benedett. Jamestown, New York 



ANSWERS TO BRAIN-BOOSTERS IN THE LAST ISSUE 



Mystery Photo: The photograph is an upside-down 
view of a chain-link fence that is covered with snow. 
Turn it right-side up and you can see some trees 
through the open spaces of the fence. 

What would happen if? The can half full of water 
would cool off fastest. Would a can of oil cool off faster 
than a can of water? 

Can you do it? If a balloon is only partly blown up, it 
might stay in one piece when popped. Also, a balloon 
filled with water should break in one piece. Does a 



balloon that is popped by being filled with too much 
air break in the same way as one that is stuck with a 
pin? 



Fun with numbers and shapes: 

Here is the solution to 
the addition problem: 



2348 
2348 
2348 
2348 
9392 



For science experts only: You could get off frictionless 
ice by blowing or by throwing some object. 



nature and science 



WALL CHART 



December 2, 1968 



the physics of 
fasteners 



CjHow many 
ways can you 
think of to fasten 
two objects together? 
Two pieces of wood, 

for example. You could hold them together 
with nails, screws, bolts and nuts, hooks and 
eyes, glue, clamps, rubber bands, string, a 
paper wrapper, or a box. You could cut parts 
out of each piece of wood to make them lock 
together (called mortising), or you could at- 
tach a ready-made mortise — a door lock — to 
them. Can you think of other ways to fasten 
them together? 

What about other kinds of materials? Can 
you think of at least six ways to hold two 
pieces of paper together? Two pieces of 
metal? Of plastic? 

Do you usually use the first kind of fastener 
you think of — or whichever kind is handiest — 
to hold things together? If so, you have prob- 
ably found that sometimes you can't i/nfasten 
objects as fast or as easily as you need to. Or 
perhaps the fastener you used didn't hold 
things together as well or as long as you in- 
tended. 

When engineers or designers choose a fas- 
tener, they first think about how the objects it 
must hold together will be used. Should they 
be held together so that neither object can 
move without moving the other, or so that 
either part can be moved without moving the 
other? Should the fastener be as strong as the 
objects it holds together, or should it be weak 
enough to "let go" before the objects it holds 
together are torn or broken apart? Will the 
fastener have to survive rubbing, pulling, 
pushing, soaking, heating, freezing, or other 
kinds of wear? How much? If you think about 
these things, you are more likely to choose a 
fastener that will do what you want it to. 

Many kinds of fasteners have been in- 
vented, or are found in nature (plant roots, 
barnacle glue, and spider silk, for example). If 
you think about a particular kind of fastener, 
you will probably find that it works in one of 
the ways shown in this Wall Chart. — F.K.L. 




Fasteners that block objects from moving apart and also pres 
on the objects are usually made of elastic materials. An elasj 
material tends to spring back to its original shape after it has 
stretched, squeezed, or bent. Wood is an elastic material, so 
presses on a nail driven into it. How does a nail hold two pie 
of wood together? Can you think of a fastener made of woodll 
that holds two objects together by pushing them apart? 




A coating of glue pressed between two pieces of wood holdl I 
together because the molecules, or tiniest particles, of glue are 
strongly attracted to the molecules of the wood. This attraction 
between molecules of different kinds is called adhesion. Will h 
adhesive fasten two pieces of wood together more firmly if tlir 
surfaces are smooth, or rough? Why? Can water be used as an 



adhesive? What for? 



Objects made of the same metal can be icelded together by 
heating adjoining parts of the objects until the metal melts, nil 
together, and hardens. This fastener works by cohesion — the 
attraction between molecules of the same kind. Can you think i 
a common plastic material that is fastened together by "weldill 
Does glue have to be strongly cohesive as well as adhesive? ^1 




^m 



Each of these fasteners holds objects together by simply 

"blocking the path" so the objects can't move apart — at least not 

in certain directions. They work because two objects can't occupy 

the same space at the same time. For example, a hutton can't pass 

through the cloth around a buttonhole, even though it can pass 

through the hole. Where is the "block" in each of the other 

fasteners? Can you think of other fasteners that work this way? 



The downward pull of the earth's gravity makes a heavy object 

hold papers together on a desk. The pull of a magnet on the 

iron frame of a refrigerator holds a shopping list in place. When 

the hollow, curved, rubber discs on the ends of the towel rack 

are pushed flat against the wall, what holds them there? 






The force that holds tiny particles together to form matter is 

electricity. There are two kinds of electricity, positive and 

negative, and a particle that carries a "charge" of positive 

electricity is attracted to a particle that carries a negative charge. 

This is the attraction that holds electrons near protons to make an 

atom, holds atoms together to make a molecule, and makes 

molecules cohere to other molecules of the same kind to make 

solid, liquid, and gaseous substances. (There are two other kinds 

of forces that hold neutrons and protons together to make the 

center, or nucleus, of an atom. Scientists are still trying to find 

out how these tiny but powerful "fasteners" work.) 



r «m i 



i science vmm 



How Fast Do Your Fingernails Grow? 




Find out how fast your nail grows by measuring each week 
the distance from a scratch to the edge of the white tip. 



■ Do you have any idea of how fast your fingernails grow? 
Here is a way you can find out. Start your investigation on 
one particular day of the week, say Monday. 

With the edge of a fingernail file (do not use anything 
sharper than that), file a short straight line across your 
thumbnail right up against the cuticle at the base of the 
nail (see photo). Next measure the distance from the 
scratch to the edge of the white band around the tip of your 
nail. Make a chart like the one shown here on a sheet of 
lined paper, and write down this measurement and the 
date you made it. 



Date 



THUMBNAIL GROWTH CHART 
Distance— Scratch to White Band 



Growth per Week 



Weeks for scratch to reach white band 



One week later, on the same day, measure the distance 
from the scratch to the edge of the white band. Has the 
scratch moved any closer to it? 

Subtracting your second measurement from the first one 
will show how much your nail has grown in one week. 
This will not be very much the first few weeks, but keep 
measuring it on the same day each week, and write down 
the date and measurement on your chart. (Every once in 
a while, you may have to deepen the scratch a little so 
that it doesn't wear away.) 

After four weeks, you will be able to tell from the 
measurements you have taken how many sixteenths of an 
inch your thumbnail has grown in one month. This will be 
10 



the rate of growth. We say that our rate of travel during a 
trip was 50 miles an hour. At the end of a month you will 
be able to say that the rate of growth of your nail is 4/16 
(or whatever) of an inch a month. When the scratch 
reaches the edge of the white band, your chart will show 
how long it took for the nail to grow one full length. 

Do you think that your thumbnail grows at the same 
rate all the time? Probably not, according to Dr. William 
B. Bean, who is a physician at University Hospitals in 
Iowa City, Iowa. Dr. Bean started measuring the growth 
of his thumbnail 27 years ago, when he was 32 years old, 
and has been taking measurements regularly ever since. 

Sometimes his thumbnail would grow more rapidly than 
usual, sometimes more slowly. Dr. Bean compared his 
record of measurements with such things as changes of 
seasons and changes of location (when he made long trips 
to Europe). But he didn't find any connection between 
these changes and the "spurts" and "lags" in his thumb- 
nail's growth. The doctor did find, though, that as he 
grew older, it took longer and longer for his thumbnail to 
grow out to its full length.— F.K.L. 



- j v r c 



Do your classmates' thumbnails grow out as fast as 
yours? Do the boys' nails grow as fast as girls'— or faster? 
Try to find answers to these questions. You might ask 
some teen-agers and some grown-ups of both sexes to 
help, too. 

On a chart like the one shown here, write the name, 
age, and sex of each person, and the date on which he or 
she marked a thumbnail. After about two months, keep 
reminding each person to watch his nail and report to 
you the date on which the scratch reaches the white band 
at the end of the nail. From these dates, you can figure 
out the "grow-out" period, in days, for each person. 

Whose thumbnail grew out fastest? Slowest? Add all 
of the grow-out periods together and divide the sum by 
the number of people involved. This gives you the 
average grow-out period for the entire group. Can you 
figure the average grow-out period for all the boys and 
girls who are about the same age? The average for teen- 
agers? For adults? Which group's nails seem to grow 
fastest? 

Is the average grow-out period for the boys in your age 
group longer or shorter than for the girls? Can you think 
of any other questions your figures might answer? Do you 
think your findings would be the same if you had been 
able to compare the grow-out periods for, say, 100 people? 

CHART OF THUMBNAIL GROW-OUT PERIODS 

Date Date Grow-out 

Name Age Sex Started Ended Period 



NATURE AND SCIENCE 




Can the Elm 
be saved 



A combination of a simple 

plant and two kinds of beetles 

is threatening to wipe out the elm 

trees of North America. Scientists are 

still trying to find a way to halt 

the deadly Dutch elm disease. 




■ When I moved to West Lafayette, Indiana, the streets 
were lined with tall, spreading elms, and the cool shade 
gave the area a calm and peaceful look. Four years later, 
however, the town seemed more like an open, sun-baked 
desert. Its elm trees were gone. Only long rows of stumps 
remained. 

Much the same thing has happened in several other 
eastern and midwestern cities. During a six-year period, 
Toledo, Ohio, for example, lost six out of every 10 of its 
elms. Kansas City, Missouri lost over 40,000 trees in just 
five years. 

What is this powerful force sweeping the country and 
threatening to wipe out all the elm trees? How does it 
work? Where did it start? Is there any way of stopping it? 

The powerful elm-killer is a fungus— a simple plant that 

December 2, 1968 



cannot make its own food. Mushrooms and molds are 
common examples of fungi. 

The fungus that does so much damage to elms lives in- 
side these trees. It clogs the tiny tubes that carry water 
from the roots to the leaves. The leaves then wilt and dry 
up, and the tree dies. This condition is called "Dutch elm 
disease," and there is no known cure for it. 

The disease got its name because it was first discovered 
in Holland. It then spread throughout Europe and Russia. 
Some of the tiny, seed-like spores of the fungus were 
brought across the Atlantic Ocean to North America in a 
load of logs. They probably arrived in the late 1920s, for 
in 1930 Dutch elm disease was discovered in Ohio. 

Since then, the disease has swept throughout half of the 

(Continued on the next page) 

11 



^- 



Beetles lay eggs 

under bark and young 

develop there. 



DISEASED ELM 



through bark. They 
carry fungus disease 
when they fly to 
healthy elms and 
feed o 



>n twigs. ,^tf_ 

_ ^ ^ — 





W/i 



HEALTHY ELM 



Fungus disease may pass 

from tree to tree when 

roots grow together. 





The Dutch elm disease has spread over the area shown in 
color, which is about half of the range of elm trees in North 
America. The diagram above shows how the Dutch elm dis- 
ease is spread from tree to tree. 

Can the Elm Be Saved? (continued) 

United States (see map). Cities that do little or nothing 
to stop it usually lose 50 to 90 per cent of their elms within 
1 years. This is very serious— elms are the most common 
trees in many cities. In Minneapolis, Minnesota, for in- 
stance, more than 90 per cent of the 650,000 trees are 
elms. Detroit and Cincinnati each have 400,000 elms; 
Dallas has 300,000; Chicago, 200,000; and Oklahoma 
City, 150,000. 

These cities do not have to lose their elms. Scientists 
have now learned much about Dutch elm disease and the 
way it spreads. A look at what they have discovered gives 
us clues about how the disease can be controlled. 

From Root to Root, from Tree to Tree 

The disease is spread in two ways. The fungus from the 
roots of an infected tree can enter directly into the roots of 

12 



any healthy elm within about 50 feet of it. This is because 
the roots of such trees often join together, forming a root 
graft. One method of controlling the disease is to dig a 
deep trench around an infected tree. The trench cuts the 
root grafts and stops the disease from spreading under- 
ground. 

The second way the disease is spread is not so simple. 
It is carried from one tree to another by two kinds of 
beedes. The European elm bark beetle is the more impor- 
tant carrier, although the American elm bark beetle will 
also do the job. 

Elm bark beetles lay their eggs under the bark of dead 
and dying elms. After the eggs hatch, the larvae (young) 
tunnel through the dead wood. Eventually they become 
adults and bore out through the bark. The beetles then fly 
to healthy elms, where they feed on the new twigs. If the 
beetles came from an elm that was infected with Dutch elm 
disease, they may carry the sticky spores of the fungus to 
the healthy trees. 

The moment a disease spore falls on an open wound in 
an elm, the tree is doomed. It may be lost in just one sum- 
mer. Sometimes it may not die for several years. 

Every branch of a dead or dying elm gives the beetles 
a new place to lay eggs. It also leaves them a large supply 
of spores to carry to healthy trees. Thus one small infec- 
tion can have almost explosive results. This was shown 
only recently in Nebraska. In 1960 the fungus was first 
found in one county. Today it infects elms in 60 counties. 

Burn Those Beetles 

One of the main methods of controlling Dutch elm dis- 

NATURE AND SCIENCE 



ease is to stop the spread of the fungus. This is done by 
sanitation— burning every bit of dead elm wood in an in- 
fected area. Then the beetles have no place to breed. 

The only problem with sanitation is that it must be com- 
plete. Even a small amount of dead elm wood can support 
many beetles. Dr. Dale Norris of the University of Wis- 
consin, in Madison, studied elm bark beetles in a labora- 
tory. He found that as many as 2,500 beetles can hatch 
from just one square foot of dead elm. "In nature, the 
average is 75 to 100 beetles," says Dr. Norris. 

Because sanitation has rarely worked alone in control- 
ling Dutch elm disease, most cities use other methods 
along with it. These involve spraying trees with poisons to 
kill the beetles. Both DDT and methoxychlor have been 
used. Although DDT is especially dangerous to birds and 
mammals, it does a better job of controlling the beetles. 

Because of the dangers of DDT, some communities 
have stopped spraying elms with this poison. In many 
places, however, city officials have decided to risk using 
DDT. 

When a combination of spraying, sanitation, and root- 
graft control is used, most elms can be saved. The city of 
Lincoln, Nebraska, followed this program and in three 








?■< 






If you tear the bark from the wood of a diseased or dead elm, 
you may find tunnels eaten into the wood by the larvae 
(young) of elm bark beetles. 

December 2, 1968 



years lost only 165 of its 130,000 elms. Most cities are 
able to hold their yearly losses to about one tree out of 
every 1 00, if they take these steps. 

But this is where a big problem comes in— a people 
problem. Most people don't take the disease seriously 
enough. Because the disease spreads so quickly, it must 
be stopped as soon as it is discovered. This takes money, 
and some cities won't spend that money. The people often 
do not believe they will lose their elms. In other cases, the 
cities may take good care of city-owned trees, but private 
owners leave their dead elms standing. This ruins the city's 
sanitation program unless laws are passed that force 
people to burn their dead elm wood. 

Not controlling Dutch elm disease is expensive. Every 
large elm that must be removed costs a city from $100 to 
$200. In addition, tree experts say that each such tree, 
when alive, is worth about $200 for its shade and beauty. 
Control of Dutch elm disease, on the other hand, costs as 
little as $3 a tree each year. 

Knowing these cost figures, the city of Detroit decided 
to control the disease. In 12 years, the city spent $lVi 
million. But during this time it saved at least $57 million 
worth of trees. 

Wasps Versus Beetles 

Scientists are trying to find new ways of stopping the 
spread of Dutch elm disease. Some of their methods show 
promise. 

One new idea is to speed up the discovery of diseased 
trees. To do so, scientists have taken pictures from air- 
planes with special film. They can then look at thousands 
of trees quickly and spot the diseased ones. If this method 
works well, it might allow foresters to find and wipe out 
Dutch elm disease as soon as it hits an area. 

Another new idea involves a tiny wasp from France. A 
female wasp lays her eggs next to the larvae of European 
bark beetles. When the eggs hatch, the wasp larvae feed 
on the beetle larvae and kill them. In Europe, this wasp 
preys only on elm bark beetles and destroys up to 70 per 
cent of them. 

Thousands of these wasps have been released in Ohio, 
Missouri, and Michigan. Already the insects have begun 
to seek out beetle larvae. If they do as well in this country 
as they have in Europe, they might really cut down on the 
spread of the disease fungus. Great numbers of these little 
wasps could be raised in laboratories. Then when a new 
outbreak of Dutch elm disease occurs, they could be re- 
leased to kill the beetles. 

With these ideas and many more being studied, Dutch 
elm disease may someday be only a worry of the past. But 
meanwhile the fungus continues to spread, and millions of 
beautiful elms remain threatened ■ 

13 






WHAT'S 
NEW 

by 

B. J. Menges 





Feeding charcoal to dairy herds 

might save farmers millions of dollars a 
year. Dairy cattle often eat plants that 
have been treated with pesticides; then 
their milk becomes contaminated. Be- 
cause federal law forbids the sale of milk 
that has any traces of pesticides, farmers 
must now discard large quantities of milk 
each year. 

Dr. Robert M. Cook, a dairy scientist 
at Michigan State University, in East 
Lansing, has found that activated char- 
coal can quickly rid an animal's body of 
pesticides. Charcoal becomes "activated" 
when it is exposed to high temperatures. 
Activation increases the ability of the 
charcoal to "soak up" and hold a liquid 
or gas. In a cow's body, activated char- 
coal takes up the pesticides, which are 
then eliminated from the body with the 
charcoal. Dr. Cook's studies suggest that 
in addition to helping the dairy industry, 
activated charcoal might be useful for 
treating people who have eaten pesticide 
poisons. 

A metal with a "memory" has 

been made by scientist William Buehler 
for the Naval Ordnance Laboratory, in 
Maryland. The metal is a combination, 
or alloy, of nickel and titanium, called 
55-Nitinol. If the alloy is formed into a 
complicated shape at a high temperature, 
then cooled and crushed into an entirely 
different shape, it will return to its exact 
previous shape when heated (see photos). 
How the Nitinol alloy can do this, when 
other materials can't, isn't known. 

The alloy could be useful in many 
fields, including space flight. Huge an- 
tennas and radio telescopes could be 
made of the alloy at high temperatures, 
then cooled and crumpled into a form 
compact enough to be carried into space. 
There, heat from the sun could expand 
the structures to their former size and 
shape. 

14 



Poisonous milkweed plants don't 
harm Monarch caterpillars. In fact, they 
help them. Monarch caterpillars feed on 
milkweed plants that contain substances 
that are harmful to most other animals. 
The caterpillars then become poisonous 
themselves, and are avoided by most ani- 
mals that would otherwise eat them. Even 
after the caterpillars turn into Monarch 
butterflies, which sip nectar from non- 
poisonous flowers, the poison remains. 




This blue jay is vomiting up a Monarch 
butterfly that scientists forced it to eat. 
Ordinarily the blue jay would never have 
eaten one of the poisonous insects. 

Eating the milkweed helps Monarchs 
in another way: Since so few animals are 
able to eat the poisonous plants, there's 
usually plenty of food for Monarch cater- 
pillars. These facts, long suspected by 
naturalists, have been confirmed in recent 
experiments by American, English, and 
Swiss scientists. 

The dawn of life on earth may 

have occurred 200 million years earlier 
than scientists have thought. Until recent- 
ly, scientists had never found a fossil that 
was more than 3 billion years old. But 
now tiny specks of matter, believed to be 
fossils, have been found in rocks at least 
3.2 billion years old. (The earth itself is 
believed to be about 5 billion years old.) 
The new discoveries are of many shapes 
and sizes. All are microscopic, some as 
small as 1 /25,000th of an inch. 

The specimens were discovered in 
South Africa by a team of researchers 
working with Dr. Albert E. J. Engel, a 





geologist at the University of California, 
in San Diego. Dr. Engel says it's unlikely 
that older fossils will be found. Earlier 
forms of life — if there were any — prob- 
ably would have been destroyed by the 
pressure and movement of the rock layers 
that built up through the ages. 

Birds guard the health of the peo- 
ple who live in New York City. Ducks, 
pheasant, quail, and chickens are kept in 
three locations around the city. A small 
amount of blood from each bird is exam- 
ined weekly by health authorities, who 
look for signs of certain insect-borne 
viruses. Some viruses, such as those of 
yellow fever and encephalitis, affect both 
birds and men. If present in the birds, the 
viruses also pose a threat to city residents. 
The birds are being watched especially 
closely these days for signs of encepha- 
litis, also known as "sleeping sickness" or 
"brain fever." In nearby New Jersey, six 
people have recently died from the dis- 
ease, which is spread by mosquitoes. 

An artificial arm that moves in re- 
sponse to signals from the brain, much 
as a real arm does, has been developed 
by scientists of the Harvard University 
Medical School, Massachusetts Institute 
of Technology, Massachusetts General 
Hospital, and Liberty Mutual Insurance 
Company, all in the Boston area. A man 
who lost most of his left arm 26 years 
ago recently had the new artificial arm 
attached to the stump of his upper arm. 
Soon he was bending the artificial arm 
at the elbow by just "thinking" about it. 

Signals from his brain cause muscles 
in the stump of his arm to contract. The 
contractions produce weak electrical sig- 
nals that are strengthened by electronic 
equipment inside the artificial arm. A 
small electrical battery, worn at the waist, 
supplies the power. The strengthened sig- 
nals run an electric motor that makes the 
arm bend. The inventors hope eventually 
to develop artificial hands and fingers that 
will also respond to "commands" from 
the brain. 



A bulky antenna could be 
formed of 55-Nitinol at high 
temperature, then cooled and 
crushed into a compact ball 
(A). The ball could then be eas- 
ily sent into space, where heat 
from the sun would make it 
gradually unfold (6) until it re- 
gained its original shape (C). 

NATURE AND SCIENCE 



Effl3 WORKSHOP 



Inside your body right now, water is moving in and out 
of cells and from cell to cell through 

a process called osmosis. With some simple equipment from 
around the house, you can investigate... 

the moving^ 
story of 



by Nancy M. Thornton 



■ Our lives are controlled by thin, soft "skins" called 
membranes. Each of the cells in your body is surrounded 
by a membrane. The membrane holds the cell together. 

Membranes have other jobs besides holding cell con- 
tents inside. All cells must get food, water, and gases, such 
as oxygen, or they die. These materials pass into the cell 
through the membrane. Wastes must pass out of the cell 
through the membrane, or the cell would become poisoned 
or would burst when it became too full. 

This Science Workshop tells how to investigate the 
way in which water passes through membranes. The move- 
ment of tiny molecules of water through a membrane is 
called osmosis. It is just one of several ways in which 
materials pass through membranes, but it is one of the 
most important ways. Here is how you can observe 
osmosis in action. 

Eggs, Straws, and Cardboard 

For this investigation you will need at least four clear 
plastic straws. Cut them into lengths of about three inches. 
You will also need some thread and some eggshells. 

Probably you remember looking at eggs and finding a 
thin white membrane just underneath the shell. If you are 
careful, you can peel large pieces of this membrane from 
eggshells. You can easily get plenty of shells if you save 
them from being thrown away after baking a cake or 
fixing breakfast. It doesn't matter if they dry out a little. 
In fact, the membranes are easier to peel if you turn the 
shells upside down for a while and drain off some of the 
egg white. 

Tie a big piece of egg membrane over one end of each 
of your straws. Be careful not to tear the membrane. If you 
do, make sure that the tear is above the place where you 
tie the membrane to the straw. Otherwise, the membrane 
will leak and you cannot be sure of your results. Wind the 

(Continued on the next page) 

December 2, 1968 





_**>&& 





15 



L 



The Moving Story of Osmosis (continued) 

thread tightly around the straw several times, then tie it. 

Support the straws in strips of cardboard (see diagram 
on this page). Do this by making X-shaped cuts in several 
places along the cardboard. Then push the open end of 
the straw through each hole. Don't try to push the mem- 
brane end of your straw through the hole; it might tear. 

Next, set the membrane-covered ends of the straws in 
water by supporting the strips of cardboard over a pan of 
water . The lower ends of the straws should not touch the 
bottom of the pan. 

Now you are ready to put liquids inside the straws. Use 
another straw for this. Push it down into a liquid, then 
cover the top end of the straw with your finger (see dia- 
gram). Lift the straw out of the liquid and put its bottom 
end inside the top of the straw you want to fill. When you 
remove your finger from the top of the straw, the liquid 
will drip out. Hold the straw so that the liquid flows down 
the side of the straw you are filling. This helps keep air 
bubbles from blocking the straw. If an air bubble forms 
(and it probably will with thick liquids), poke the bubble 
with a toothpick until it is broken and the air escapes. 
Rinse off the toothpick and "filler" straw with warm 
water before working with the next liquid. 



INVESTIGATIONS 



• Fill one straw with water, and another with syrup. 
Suspend both in syrup. What happens? Does it make 
any difference if you put each straw in a separate 
syrup container instead of in the same container? 
(You can use the same straws for different investi- 
gations if you empty and wash them thoroughly be- 
fore use.) 

• Suspend an empty straw (covered with a mem- 
brane) in water and see what happens. You might 
also try empty straws suspended in different syrups. 

• Try different membranes. Instead of using egg 
membrane, use a straw poked into a very thin slice of 
raw potato or carrot. Try a man-made membrane, 
such as cellophane or waxed paper. Use a double egg 
membrane and see if this makes any difference in 
the flow of liquids in or out of a straw. You might 
even try filling a plastic bag as full of water as pos- 
sible, then suspending it in heavy syrup and seeing 
what happens. 

• Now that you've observed osmosis with sugar 
solutions, try other types of solutions. For instance, 
make a salt solution and suspend a straw filled with 
this in water or different syrups. You might also try 
milk or other liquids. 



Which Way Do the Liquids Flow? 

After you put a liquid inside each straw, write the name 
of the liquid on the cardboard near the straw, so you will 
know what is in it. Fill the first straw about halfway with 
water. This will be your control, with which you can com- 
pare the other liquids. Use a piece of tape to mark the 
level of the water. 

Make a sugar solution by stirring as much sugar as you 
can into warm water. Stop adding sugar when you see 
sugar collecting at the bottom of the container. Fill a straw 
halfway with this solution and mark the level of the 
solution. 




CARDBOARD STRIP 



Fill other straws to the same level with syrup, using dif- 
ferent kinds such as corn syrup, maple syrup, and so on. 
Remember to mark the level of the liquid on each straw. 
Also use a very thick sugar solution, such as molasses or 
sorghum. If these liquids are too "stiff," you can increase 
the flow by warming them slightly. Don't mark the level 
until each of the substances has flowed down the inside of 
the straw. If any of the liquid drips on the outside of the 
straw, clean it off before it reaches the water in the pan. 
To avoid this problem, you can "load" the straws before 
setting the cardboard supports over the water. 

Leave the straws undisturbed, making sure that the 
membrane-covered ends do not touch the bottom of the 
water container. Check the levels each hour for about 
three hours. 

You will probably find that the liquid levels have 
changed. If the liquid inside the straw has risen above the 
mark you made, then water has passed through the mem- 
brane into the straw. If the liquid has dropped below the 
mark, then some of it has passed through the membrane 
out of the straw. Remember that the weight of the liquid 
column within the straw will have some effect toward 
emptying the straw. Does it in the control straw? 

Have some of the sugar solutions (including the syrups) 
risen or fallen farther in the straws than others? What do 
you think might happen to a cell, full of dissolved sugar, 
that is surrounded by water? What might happen to a 
water-filled cell that is surrounded by a very thick sugar 
solution? ■ 



16 



NATURE AND SCIENCE 



Using This Issue .. . 

| (continued from page 2T) 

of the beetle larvae. Also, some species 
j of elm, such as the Siberian elm, have 
j evolved a resistance to the fungus dis- 
; ease. (In the United States, botanists 
are trying to produce a hybrid elm with 
' the appearance of the American elm 
j and the disease-resistance of the Si- 
; berian species.) 

The use of natural enemies, such as 

! this wasp, to control diseases and dis- 

| ease-carriers, is getting more attention 

from scientists who are seeking sub- 

i stitutes for indiscriminate control 

! methods such as DDT. (For more in- 

j formation on the far-reaching effects 

\ of DDT and other biocides, see "Can 

We Save the Eagles?", N&S, March 18, 

1968.) 

Even if the European wasp is suc- 
cessful in reducing the numbers of elm 
bark beetles, the Dutch elm disease 
may continue to be a problem in North 
America. Where elm trees grow close 
together, up to 60 per cent of the in- 
fections occur underground, through 
root grafts. 

Osmosis 

After investigating the effects of 
osmosis, your pupils will wonder how 
and why it takes place. You might ex- 
plain it in this way: 

The molecules (see bottom right 
caption on page 9) of a substance are 
always moving around in different di- 
rections (the movement is faster in a 
gas than in a liquid, and faster in a 
liquid than in a solid). When two mole- 
cules collide, each bounces away in a 
new direction. If there are many mole- 
cules in a small volume (such as an 
open jar with perfume in it), a mole- 
cule moving in any direction except 
out of the jar will eventually hit an- 
other perfume molecule or the wall of 
the jar. It will change direction as a 
result of the hit. But a molecule mov- 
ing out of the jar will hit only the 
lighter molecules of oxygen and nitro- 
gen (air), which do not deflect the 
heavier perfume molecule very much. 
So it keeps moving away from the jar. 
As more and more molecules move out 
of and away from the jar, the perfume 



becomes more and more evenly dis- 
tributed throughout the air. 

This movement of molecules from a 
place where they are plentiful to a 
place where there are fewer molecules 
of the same material is called diffusion. 
Osmosis is a special case of diffusion— 
the diffusion of water molecules 
through a semi-permeable membrane 
(one that lets certain kinds of mole- 
cules pass through it more easily than 
others). 

Egg membrane is semi-permeable 
and allows water molecules to move 
from the reservoir, where they are 
plentiful, into the straws, where they 
are fewer. (The stronger the sugar solu- 
tion, the fewer water molecules it con- 
tains.) Sugar molecules are larger and 
do not pass through the tiny holes in 
the membrane as easily as water mole- 
cules. Otherwise, many sugar mole- 
cules would probably diffuse from the 
straws into the reservoir. 

Osmosis helps keep a living cell in 
balance with its liquid environment. 
For example, when salt builds up in 
the watery solution in a cell, water 
enters the cell by osmosis and weakens 
the solution; if the interior solution is 
too weak, some water leaves the cell 
by osmosis, strengthening the solution 
inside. 

Bra in- Boosters 

Mystery Photo. The jar in the photo 
contains oil, a melting ice cube, and 
large drops of meltwater from the ice 
cube. The fact that the ice floats while 
the water sinks means that the density 
of the oil is somewhere between that 
of ice and water (see "How Dense Are 
You?\' N&S, Sept. 30, 1968). 

What would happen if? Your pupils 
can discover for themselves that the 
bottle containing the smaller amount 
of water will make the higher-pitched 
sound when it is tapped. Can they 
guess which bottle will make the 
higher-pitched sound if someone blows 
across the top of each bottle? 

Tapping a bottle makes the glass 
vibrate back and forth, producing 
sound waves in the air. The faster the 
glass vibrates, the more sound waves 
reach your ear each second and the 
higher the pitch of the sound you hear. 



Water in a bottle slows down the vibra- 
tion of the glass, so the more water 
there is in a bottle, the lower the sound 
it will make when tapped. 

When you blow across the opening 
of a bottle, however, it is the air in the 
bottle that vibrates and produces sound 
waves in the surrounding air. The 
shorter this "column" of air, the faster 
it vibrates and the higher the pitch of 
the sound you hear. 

Can you do it? Some of your pupils 
may try to release "one eighth of a 
drop" from a medicine dropper or a 
straw. Let them see that no matter how 
hard they try, they cannot change the 
size of the drop coming from the same 
straw or dropper. 

One way to obtain a glass of water 
containing one eighth of a drop of 
milk is by serial dilution: First use a 
straw to place one drop of milk into 
a glass of water. Stir the mixture, then 
dump out half and add more water un- 
til the glass is filled again. If you repeat 
this procedure twice more, the final 
glass of water will contain one eighth 
of a drop of milk. If you use food color- 
ing liquid instead of milk, the effect of 
each dilution will be more visible. 

Have your pupils try to think of 
other ways to dilute the milk. One 
easy way would be to put the drop of 
milk into a half-gallon (64 fluid 
ounces) of water; then pour off one 
cup (8 fluid ounces), which will con- 
tain one eighth of a drop of milk. 

Fun with numbers and shapes. 
Pupils who answer this question too 
quickly will probably say that the chest 
has seven drawers. Have someone 
draw a model on the blackboard to 
show that the chest can only have six 
drawers. 

For science experts only. There are 
many possible ways for the oil to have 
"changed" into ice. (Someone could 
have dumped out the oil and filled the 
pan with water.) 

In this case, the pan had been placed 
under the edge of the garage roof, 
where rain could run into it. The rain- 
water sank through the less dense oil 
to the bottom of the pan. As water 
filled the pan, the oil floating on the 
water ran over the top of the pan and 
onto the ground. When winter came, 
the water froze. 






December 2, 1968 



3T 



Books That Will Help You . . . 

(continued from page IT) 

plus several student experiments and pic- 
torial riddles. 

The topic areas of the lessons are those 
suggested by the recent national Feasibil- 
ity Conference on elementary science 
education sponsored by the American 
Association for the Advancement of Sci- 
ence. Outstanding scientists, teachers, 
supervisors, and science educators listed 
these topics as the most important for the 
elementary school. The concepts in- 
volved in each lesson are taken from the 
list of principles of science considered by 
scientists to be important for any person 
having a general education. No effort was 
made, however, to cover all the concepts 
and principles that may be embodied in 
an elementary curriculum. 

The lessons are organized in depart- 
mental areas (physical science, earth sci- 
ence, biological science), and sugges- 
tions for using the lesson plans are 
made in the introduction to each section. 
Each plan has designated grade levels 
and an easy-to-follow form — Concepts, 
Procedure (step-by-step), and Student 
Activities. Twelve suggestions for using 
the discovery approach can be found on 
pages 167-168. 



Science in Elementary Education, by 

Peter C. Gega (John Wiley and Sons, 
1 966, 45 1 pp., $8.95) . This is "a book on 
how to teach science in elementary 
schools," as states the author's preface. 
The first part of the book introduces the 
basic things teachers need to know, while 
the 12 chapters (or "units") of Part II 
are the heart of the book. They contain 
model lesson plans arranged in teaching 
sequences that encourage children to 
learn through the development of their 
own critical thinking skills. These skills 
are clearly identified as they arc used 
within each lesson. A subject-matter dis- 
cussion before each sequence of lessons 
provides the background needed to teach 
the sequence confidently and success- 
fully. 

There are four units each at the pri- 
mary, intermediate, and upper-grade 
levels — enough material in the life, earth, 
and physical sciences to make up most of 
a year's work at each level. Each unit has 
the same format: an introductory state- 
ment, a list of Basic Generalizations, a 
brief discussion of the topic, then a devel- 
opment of each Basic Generalization 
with materials, activities, and explicit 
directions. 

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ANIMALS THROUGH THE 
AGES (#101)— A fascinating study 
of prehistoric animal life, including 
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INVESTIGATIONS IN MATTER 
AND ENERGY (# 102)— Intro- 
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Covers various aspects of wildlife, 
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NATUKI l.\/> M IF.NCE 



nature and science 

TEACHER'S EDITION 

VOL. 6 NO. 7 / DECEMBER 16, 1968 / SECTION 1 OF TWO SECTIONS 

COPYRIGHT © 1968 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 



4 N & S REVIEWS ► 

Books That Will Help You 
Teach Science 

by Dulcie I. Blume 

This is the second of three reviews of some books published in the past five 
years that have earned a front-row position on the shelves of elementary 
school teachers of science. Many were written by people with years of ex- 
perience in teaching science to children. All of these books will help you to 
answer questions . . . to develop and direct investigative activities . . . to create 
classroom situations from which your pupils will be propelled to their own 
investigations, observations, and books. 



Elementary Teacher's Classroom Sci- 
ence Demonstrations and Activities, by 

David E. Hennessy (Prentice-Hall, 1964, 
308 pp., $8.95). Here is a book particu- 
larly designed to help elementary school 
! teachers who are not specialists in sci- 
ence. The demonstrations and activities 
presented can be incorporated into any 
elementary science program, and the 
I areas of science included should be of in- 
terest to all elementary school children. 
: Plants and animals, electricity and mag- 
netism, earth and sky, and rockets and 
space travel are some of the topics 
covered. 

The demonstrations and activities — all 
I tested in school situations — emphasize 
I the use of inexpensive materials and 
equipment that can be easily obtained at 
: home, from the school custodian, from 
[ the local junkyard or at the five and dime. 
: Cautions are included where necessary. 
Each activity and demonstration is de- 
! veloped according to the same pattern — 
\ Materials, Procedure, Discussion. One of 
! the simplest activities, called "Seeing Be- 
} hind You," requires just five lines for 
development, while one of the more com- 
plicated activities — making a schoolyard 
map by triangulation — is given more 
than two pages. Grade levels from kin- 
dergarten through grade six are suggested 
for each activity, but this does not mean 

Mrs. Dulcie I. Blume is Coordinator of Cur- 
riculum Materials of the Alameda County 
School Department, Hayward, California. 



that the activity is limited to those levels. 
Each teacher can plan the science pro- 
gram to suit the children's needs. 

With its many clear illustrations, its 
simple language, and its easy directions, 
this is a book that could be used by the 
children themselves. 

Experiences with Living Things: an 
Introduction to Ecology for Five- to 
Eight- Year-Olds, by Katherine Wens- 
berg (Beacon Press, 1966, 143 pp., 
$4.95). The book is planned as a guide 
for the teacher who undertakes back- 
yard explorations with boys and girls of 
kindergarten and early primary age. Chil- 
dren are eager to learn about the natural 
world around them, and a study of 
ecology will prove most successful if 
it involves their own exploration. Guiding 
such a venture means providing resources 
for the answering of questions, and giving 
the kind of adult leadership, stimulation, 
and direction that can keep the activity 
exciting and rewarding. 

The book presents a rich variety of 
experiences that are not planned to be 
covered in any specific length of time. 
When the teacher feels that the children 
have had ample time to savor the ex- 
perience and have gained all that they are 
going to gain at this time, then there is a 
story to turn to at the end of each ex- 
perience. These stories are emphatically 
not introductions to the experiences, but 
rather summaries of them. There are also 
(Continued on page 4T) 




IN THIS ISSUE 

(For classroom use of articles pre- 
ceded by •, see pages 2T and 3T.) 

• 100 Turtle Eggs 

A scientist finds out how the number 
of eggs a sea turtle lays may help 
the species to survive. 

• Brain-Boosters 

Lighting the Way for Plants 

Your pupils can investigate how a 
light deficiency affects plants. 

Round Trip to the Moon 

A Wall Chart shows the Apollo 
spacecraft, its Saturn V rocket, and 
the travel plan for landing men on 
the moon within the coming year. 

• Exploring Radio Waves 

Your pupils can find out quite a bit 
about how radio waves travel with a 
dry cell, some wire, and a portable 
radio receiver. 

The "Giants" of Easter Island 

A famous archeologist persuaded 
people of the island to show him 
how their ancestors may have carved 
the huge statues and moved them 
to platforms around the island. 

How Fast Does the Wind Blow? 

Your pupils can investigate the re- 
lation of wind speed and direction 
to changes in the weather. 

IN THE NEXT ISSUE 

How to investigate the formation of 
ice in lakes and ponds . . . Tracking 
animals in the snow . . . The myster- 
ies of how sea turtle hatchlings find 
their way to the sea and where they 
go when they get there. 



USING THIS 

ISSUE OF 

NATURE AND SCIENCE 

IN YOUR 

CLASSROOM 



100 Turtle Eggs 

For a species of animal or plant to 
survive, it must produce some young 
that live long enough to have offspring 
of their own. Through the process of 
natural selection, green sea turtles have 
evolved a way of reproduction that has 
enabled them to survive for millions of 
years. 

Whether sea turtles can survive ex- 
ploitation by humans is still in doubt. 
Humans prey upon sea turtles where 
they are most vulnerable— on the nest- 
ing beaches. Adult turtles are killed 
and their nests robbed. Huge nesting 
colonies have been wiped out and the 
number of wild, protected beaches is 
becoming scarce. 

There are six main ways in which 
organisms are adapted to reproduce 
successfully (see "Six Ways to Suc- 
cess," N&S, March 27, 1967, or Wall 
Charts — Set 2). For sea turtles, the 
key to success is producing many 
young. A female turtle comes ashore 
about four times in the nesting season, 
each time laying about 100 eggs in a 
nest. 

Have your pupils name examples of 
other species that produce great num- 
bers of young. Fish and insects are 



NATURE AND SCIENCE is published for The American 
Museum of Natural History by The Natural History 
Press, a division of Ooubleday & Company, Inc., fort- 
nightly September, October, December through March; 
monthly November, April, May, July (special issue). 
Second Class postage paid at Garden City, N.Y. and at 
additional office. Copyright ' 1968 The American 
Museum of Natural History. All Rights Reserved. Printed 
in U.S.A. Editorial Office: The American Museum of 
Natural History, Central Park West at 79th Street, 
New York, N.Y. 10024. 

SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester 
per pupil, $1.95 per school year (16 issues) in quanti- 
ties of 10 Or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's 
edition $5.50 per school year. Single subscription per 
calendar year (17 issues) $3.75, two years $6. Single 
copy 30 cents. In CANADA $1.25 per semester per 
pupil, $2.15 per school year in quantities of 10 or more 
subscriptions to the same address. Teacher's Edition 
$6.30 per school year. Single subscriptions per cal- 
endar year $4.25, two years $7. ADDRESS SUBSCRIP- 
TION correspondence to: NATURE AND SCIENCE, The 
Natural History Press, Garden City, N.Y. 11530. Send 
notice of undelivered copies on Form 3579 to: NATURE 
AND SCIENCE, The Natural History Press, Garden City, 
N.Y. 11530. 



good examples; some species of fish 
produce millions of eggs. Other ani- 
mals, such as mice and rabbits, have 
only about four young per litter, but 
have several litters a year. 

Your pupils can probably guess the 
key to reproductive success in humans: 
parental care. Humans provide more 
of this than any other animals do. Sea 
turtles give no parental care; the adults 
never see their young. Animals that 
give no parental care are usually 
adapted to produce many young. 
Those species that give parental care 
can survive by having fewer young, 
since more individuals survive. 

For more information about the 
lives of sea turtles, see "The Voyages 
of the Green Turtle," N&S, Nov. 1, 
1965. 

Exploring Radio Waves 

(This Science Workshop and the Activity 
suggested below are based on ideas from 
"Radio Waves" and "Direction Finding by 
Radio," by Hy Ruchlis, in Science and 
Children, Sept. and Oct., 1967, and are pub- 
lished by permission. Mr. Ruchlis is Adjunct 
Professor of Education and Director, Edu- 
cational Media Center, Fairleigh Dickinson 
University, Rutherford, N.J.) 

Have your pupils make these inves- 
tigations alone or in small groups, at 
home or in the classroom, keeping rec- 
ords of their findings to report and 
compare in a class discussion. Where 
their results from a particular test 
agree, have your pupils try to make up 
a simple statement that summarizes 
their findings. For example, they 
should find that starting and stopping 
the flow of current through the "trans- 
mitter" wire causes a noise to come 
from the loudspeaker of the radio re- 
ceiver. They know that the receiver is 
made to detect radio waves in space 
and change them into sound waves. 
So they might summarize their finding 
thus: When an electric current is made 
to start or stop flowing through a wire, 
radio waves are sent out from the wire 
and can he detected and changed into 
sound waves by a nearby radio receiv- 
ing set. 

When your pupils report different 
results from a particular test, suggest 
that each individual (or group) repeat 
the test to see whether he gets the same 
results as before. If results from the 



test still vary widely, have your pupils 
try to find out why. Making the tests 
with each others' equipment might 
show that weak cells in a transmitter 
or receiver would account for the dif- 
ferences. Or watching each other make 
the tests may turn up some differences 
in procedure that make results differ. 

As agreement is reached on the re- 
sults of each test, have your pupils 
summarize the findings in a statement 
that describes their findings but does 
not go beyond them. When this has 
been done for each of the tests sug- 
gested in the article, have your pupils 
compare the summary statements with 
each other to make sure none are con- 
tradictory. (This is a good project in 
perception and descriptive writing, as 
well as in scientific research.) 
• Your pupils can get a good idea 
about how radio waves are made by 
reading and doing the projects in 
"Electricity from Magnets" and "See- 
ing Things in Different Lights" (N&S, 
March 18,1968). 

Activity 

Using a portable receiver to locate 
the transmitter of a radio broadcasting 
station will help your pupils find out 
for themselves how scientists use ra- 
dio receivers to locate and "follow" a 
wild animal that has had a tiny radio 
transmitter attached to its body. 

You will need a transistor radio with 
an inside bar antenna whose position 
in the set can be seen by removing the 
back. As your pupils have probably 
discovered, the broad side of a bar an- 
tenna detects radio waves more effec- 
tively than the narrow end of the 
antenna does. This means that when 
the set is turned so that it receives a 
station's signal least well, one end of 
the receiver's bar antenna must be 
pointed toward the transmitter (see 
diagram on page 3T). 

A road map of your area and a 
compass to help your pupils to turn 
the map's north end toward the North 
Pole will be helpful. Have your pupils 
find and mark the location of your 
school on the map. 

When your pupils have seen how 
the bar antenna "points" inside the re- 
ceiver, replace the back and stand the 
(Continued on page 3T) 



2T 



NATl RE INDSCIENCl 




How did huge 

statues like these 

get around a remote 

Pacific island? 

spe page 1 1 

THE 'GIANTS'' OF 
STER ISLAND 






nature and science 

VOL. 6 NO. 7 / DECEMBER 16, 1968 

CONTENTS 

2 100 Turtle Eggs, by Archie Carr 

5 Brain-Boosters, by David Webster 

6 Lighting the Way for Plants, 

by Nancy M. Thornton 

8 Round Trip to the Moon 

10 Exploring Radio Waves 

1 1 The "Giants" of Easter Island, 

by Carrol Alice Stout 

1 5 How Fast Does the Wind Blow?, 

by Franklyn M. Branley 

16 What's New?, by B. J. Menges 



PICTURE CREDITS: Cover, pp. 11-14, photos by George Holton; pp. 3, 5-11, 
15, drawings by Graphic Arts Department, The American Museum of Natural 
History; p. 2, Dr. Archie Carr; p. 4, top from Dr. Archie Carr, bottom by 
Jo Conner; p. 5, photo from David Webster; p. 16, courtesy of Lockheed 
Aircraft Corporation. 



PUBLISHED FOR 

THE AMERICAN MUSEUM OF NATURAL HISTORY 

BY THE NATURAL HISTORY PRESS 

A DIVISION OF DOUBLEDAY & COMPANY, INC. 

editor-in-chief Franklyn K. Lauden; executive editor Laurence P. 
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garet E. Bailey, Susan J. Wernert; editorial assistant Alison New- 
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Donald B. Clausen • consulting editor Roy A. Gallant 

publisher James K. Page, Jr.; circulation director J. D. Broderick 
promotion director Elizabeth Connor 
subscription service Frank Burkholder 

NATIONAL BOARD OF EDITORS 

PAUL F. BRANDWEIN, CHAIRMAN, Dir. of Research, Center for Study of 
Instruction in the Sciences and Social Sciences, Harcourt, Brace & World. Inc. 
J. MYRON ATKIN, Co-Dir., Elementary-School Science Project, University of 
Illinois. THOMAS G. AYLESWORTH. Editor, Books for Young Readers, 
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Schools, New York City. RAYMOND E. BARRETT, Dir. of Education, Oregon 
Museum of Science and Industry. MARY Bl.ATT HARBECK, Science Teach- 
ing Center, University of Maryland. ELIZABETH HONE, Prof, of Education, 
San Fernando (Calif.) State College. GERARD P1EL, Publisher, Scientific 
American. SAMUEL SCHENBERG. Dir. of Science, New York City Board of 
Education. WILLIAM P. SCHREINER, Coord, of Science, Parma (Ohio) City 
Schools. VIRGINIA SORENSON, Elementary Science Consultant, Dallas In- 
dependent School System. DAVID WEBSTER, Staff Teacher, Elementary 
Science Study, Educational Development Center. Newton. Mass. • REPRE- 
SENTING THE AMERICAN MUSEUM OF NATURAL HISTORY: FRANK- 
LYN M. BRANLEY, Chmn., The American Museum-Hayden Planetarium. 
RICHARD S. CASEBEER, Chmn., Dept. of Education. THOMAS D. NICH- 
OLSON. Asst. Dir., AMNH. GORDON R. REEKIE, Chmn., Dept. of Exhibi- 
tion and Graphic Arts. DONN E. ROSEN, Chmn., Dept. of Ichthyology. 
HARRY L. SHAPIRO, Curator of Physical Anthropology. 

NATURE AND SCIENCE is published for The American Museum of Natural History by 
The Natural History Press, a division of Doubleday & Company, Inc., fortnightly 
September, October, December through March, monthly November, April, May, July 
(special issue). Second Class postage paid at Garden City, NY. and at additional 
office. Copyright © 1968 The American Museum of Natural History. All Rights Re- 
served. Printed in U.S.A. Editorial Office: The American Museum of Natural History, 
Central Park West at 79th Street, New York, N.Y. 10024. 

SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester per pupil, $1.95 per school 
year (16 issues) in quantities of 10 or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's edition $5.50 per school year. 
Single subscription per calendar year (17 issues) $3.75, two years $6. Single copy 30 
cents. In CANADA $1.25 per semester per pupil, $2.15 per school year in quantities 
of 10 or more subscriptions to the same address. Teacher's Edition $6.30 per school 
year. Single subscriptions per calendar year $4.25, two years $7. ADDRESS SUB- 
SCRIPTION correspondence to: NATURE AND SCIENCE, The Natural History Press, 
Garden City, N.Y. 11530. Send notice of undelivered copies on Form 3579 to: 
NATURE AND SCIENCE, The Natural History Press, Garden City, N.Y. 11530. 




It is no accident that a sea turtle lays 

about this number of eggs in a nest in 

the sand. Fewer eggs, or more, and 

the turtle species might 

not survive. 



This article is adapted in part from the hook, So Excellent a Fishe, 
hy Archie Carr, published by The Natural History Press, Garden 
City, N.Y. Copyright © 7967 hy Archie Carr. 



NATURE AND SCIENCE 



■ When I set out more than 1 years ago to write a book 
about North American turtles, I found that little was 
known about big sea turtles. This bothered me, and I 
began roaming the Caribbean Sea looking for whatever 
could be learned about them. 

There are two times when a zoologist (a scientist who 
studies animals) can count on observing sea turtles: when 
a female goes ashore to lay her eggs in a hole in the sand, 
and when the young turtles hatch from the eggs. One of 
the most amazing things zoologists have learned is that 
the female usually lays about 100 eggs in her nest. She 
may lay as few as 20, or as many as 200, but the average 
number of eggs in a nest is 100 for sea turtles. But why? 
Why not 2 eggs, or 30, or 1,000? 

I'm sure that the number is no accident. As sea turtles 
have evolved, or slowly changed over millions of years, 
100 eggs to a nest became the average because this is the 
number that helps to ensure the survival of the sea turtle 
species. By studying sea turtles for many years, I learned 
some of the reasons for this special number. 

A Gauntlet of Death 

One reason that sea turtles lay 100 eggs is that most 
of the eggs — or the young that hatch from them— are 
bound to be eaten by other animals. The turtles' enemies 
range in size from ants and crabs to bears and tigers. 

A turtle nest is safe from most enemies during most of 
the 60 days it takes the eggs to hatch. The egg-eaters are 
a menace while the eggs are being laid and for a day or two 
afterward. After that, however, there is a peaceful period 
when no animal seems able to find the turtle eggs buried 
in the sand. Why this is, nobody knows. 

But then comes the time for hatching and coming out 
of the nest. For a few weeks there may be little turtles 
(hatchlings) by the thousands on the beach. For them, the 
danger begins when they have dug almost to the surface 
of the sand. 

They lie there for a while as if waiting for some signal 
—for the thin crust over the nest to reach a certain tem- 
perature, perhaps. Whatever it is they wait for, it usually 
happens at night, most often after midnight, and most often 
during or after light rain. 

When the turtles come out of the nest, they waste no 
time about it. Their trip across the sand to the surf is fast 
and direct. This time of greatest danger is only a minute 
or two, or a little longer if the way to the sea is blocked 
by many objects. The little turtles come out into a world 
eager to eat them, and they have to go fast and straight 
toward the ocean even though they can't see it and have 

December 16, 1968 



never seen it. This is certainly one reason the mother 
turtle has to lay so many eggs. 

Spying on Turtle Nests 

It seems that many eggs being laid together helps more 
turtles to survive than if the eggs were laid singly. Some 
other scientists and I were able to watch the things that 
go on in sea turtle nests by digging up to a nest from one 
side and replacing the sand wall with a pane of glass. Or 
we reburied eggs at the usual depth in a box of sand, put- 
ting them against a glass pane at one end of the box. 

The first turtles that hatch from the pile of eggs do not 
start digging at once, but lie still until some of their nest- 
mates are free of their eggs. Then turtles on top of the pile 
scratch down the nest's ceiling. Those around the sides 
dig at the walls. Those on the bottom trample and pack 
the sand that filters down from above, and they keep the 
hatchlings above them stirring. The ceiling falls, the floor 
rises, and the roomful of turtles working together moves 
toward the surface (see diagram). 

To test the real usefulness of this teamwork, we buried 
single eggs as deep as in a typical nest and watched what 
happened to them. Out of 22 eggs that hatched singly, 
only six of the young reached the surface of the sand— 
and all these were too weak to go on across the sand to the 
water. As we added more eggs to these test groups, more 
hatchlings got to the surface. A 10-turtle team, however, 
seemed just as able to reach the surface as a group of 100. 

(Continued on the next page) 



The newly-hatched tur- 
tles work their way to 
the surface as a team. 
The turtles at the top 
and sides of the nest 
dig upward while those 
near the bottom pack 
down the sand that falls 
from above..;/ -.-v. v--..-' *"£. 




IfiP'^ 



■>ir i-.^?t-.-;*ui 




These young green turtles were hatched in a laboratory, 
then released among the dunes of a Florida beach. They 
had never seen the ocean before but found their way directly 
to it, crossing this channel and steep sand bar along the way. 

100 Turtle Eggs (continued) 

There are other advantages in the big groups. The 
turtle teamwork continues during the trip from the nest 
to the surf. In tests with young hawksbill turtles, we 
allowed hatchlings to crawl one by one across the beach. 
They stopped more often than those traveling in groups. 
The single turtles seemed to lie still longer during stops 
and to go less surely toward the surf. So single turtles are 
on the open beach longer and are more likely to be caught, 
or, if they have come out of their nest during the day, to 
dry up in the hot sun. 

When a nestful of hatchlings comes out all at once or 
in a few smaller groups, periods of stopping are fewer and 
shorter because the turtles keep bumping one another. We 
found some evidence that the path of a big group of hatch- 



lings usually goes more directly toward the sea than that 
of turtles traveling separately. 

These advantages are almost surely part of the reason 
that sea turtles lay a lot of eggs intsead of only one. There 
are probably many more reasons. 

Why Not More Eggs? 

If 100 eggs in a nest are needed to help sea turtles 
survive, it seems that there would be advantages in pro- 
ducing a great many more eggs. One way to increase the 
number of eggs would be to make each egg smaller. But 
then the amount of food stored in the egg for the un- 
hatched turtle would have to be reduced. This would 
make each hatchling smaller and turn it out into the world 
less able to scramble, to resist drying up, and to get through 
its first year in the ocean. 

If a turtle produced more eggs of the normal size, it 
would almost surely be overburdened. Even if the female 
turtle could carry more eggs to the beach, she would prob- 
ably have trouble housing the bigger group in a proper 
nest. A proper nest is one with the right temperature and 
humidity, and a "roof" thick enough to hide the eggs. 
These needs probably affect the size of the nest the female 
digs, which is just right for 100 eggs. 

Once you think about it, it seems that almost everything 
a species of sea turtle does, or that happens to it, is re- 
flected in some way in those 100 eggs or so the female 
drops into the hole she digs in the sand ■ 

In the next issue, the author tells what has been learned so far 
about how the young sea turtles find their wax to the sea. and 
where they go after they disappear in the surf. 



m 



•V 







To learn more about the nests 
of sea turtles, Dr. Carr and 
his assistants dig into many 
nests to measure their depth 
and to count the eggs. Here, 
Mimi Carr, the author's 
daughter, and Shefton Mar- 
tinez B. explore a nest on a 
Costa Rican beach. 




\ Ml Kl l\l> \( II \' I 




MYSTERY 
PHOTO 

How did the 
icicle get 
to the middle 
of the wire? 



Ot* 





prepared by DAVID WEBSTER 



WHAT 
WOULD 
HAPPEN 
IF... 



. . . the turntable were spun around slowly at first, then 
faster and faster? In what order would the wood blocks 
slide off? 

CAN YOU DO IT? 

Can you "float" a needle in a glass of soapy water? 

JUST FOR FUN 

Last year we told how to clean dirty pennies by putting them 
in a mixture of salt and vinegar. Catsup can also be used 
to brighten pennies. Put some catsup on an old penny and 
wash it off after a few hours. 



FOR SCIENCE EXPERTS ONLY 

A fly is flying around in a moving train. When the train 
stops, will the fly go backward, forward, or stay where it is 
in the car? 

Submitted by John Mazzarella, Philadelphia, Pennsylvania 



FUN WITH NUMBERS AND SHAPES 

The solid black line is a ditch that is being dug for a water 
pipe that will go through the corner of the house and out 
the other side in a straight line. How can the builders draw 
the broken line, to guide them in digging the rest of the 
ditch, without making any measurements? 



&&$&? 




ANSWERS TO BRAIN-BOOSTERS IN THE LAST ISSUE 



Mystery Photo: The jar in the photo contains oil, a melting 
ice cube, and drops of water from the melted ice. Why does 
the ice float in the oil if the water sinks to the bottom? 

What will happen if? The bottle containing the smaller 
amount of water sounds the higher note when you tap it. 
Will that same bottle sound the higher note if you blow across 
the opening of each bottle? 

Can you do it? To make a glass of water that contains just 
one eighth of a drop of milk, first use a straw to place one 
drop of milk into a full glass of water. Stir the mixture, then 
dump out half and add more water until the glass is filled 



again. Do this twice more, and you will have one eighth of a 
drop of milk in the water. How could you make a glass of 
water that contained one fifth of a drop of milk? 

Fun with numbers and shapes: There are six drawers in the 
chest. 

For science experts only: The pan of oil happened to be 
placed under the edge of the garage roof, where rain would 
run into it. Rainwater is denser than oil, so the rainwater sank 
to the bottom of the pan. As the pan filled with water, the oil 
floating on the water ran over the top of the pan and onto the 
ground. When winter came, the water in the pan froze. 



December 16, 1968 



SCIENCE M iMlilil 



LIGHTING 

the WAY 
for PLANTS 




by Nancy M. Thornton 

Green plants cannot survive for long 
without light. Here are some ways for you 
to find out how much light they need. 



■ Peek under a porch, and you'll find very few green 
plants. Nor can many grow under a thick clump of trees. 
Green plants seem to need light. But how much light do 
they need? Does darkness always mean death for them, 
or does it result in plants that grow in strange ways? In this 
Science Workshop, you can investigate the relationship 
between green plants and light— and you'll be able to eat 
some of your results! 

You will need a packet of radish seeds, some soil, and 
four empty milk cartons. Half-gallon milk containers are 
good for growing radishes. Cut or punch several small 
holes in the bottoms so that excess water can drain away. 
Also put a layer of facial tissue on the bottom of each 
carton so that the soil will not drain away with the water. 
Fill the bottom of each carton with soil about five to six 
inches deep. Then put 10 radish seeds on top of the soil 
and cover them with '/8-inch of soil. Sprinkle water on the 
soil until it is thoroughly damp. Once the radishes start 



! 



growing, thin them so there are only three or four in each 
carton. 

The diagrams on this page show what you should do to 
the cartons to test the effects of different lighting conditions 
on radish seedlings. 



LIGHT PLANTER 



top open 

carton cut to 
7 inches high 

5-6 inches of soil 



saucer 







liS*** 








IX !\\*X\\\vI 




'c 


"£&•&•:• 


>i|x£i£££^ 


S 



DARK PLANTER 



tape 




cardboard top 

After planting, 
tape black paper 
to sides of carton. 
Cover open top! 
with cardboard. 



DARK PLANTER WITH WINDOW 



Prepare carton like 
dark planter. Then 
cut a small window 
in the side of the 
planter. Window 
should face light. 




window 



SHADED PLANTER 




After planting, 
tape black paper 
to sides of carton 
Leave top open. 



I 











.IGHTING CONDITION IN CARTON: ( 




First 
observations 


Second 


Third \ 


Date 








Color and 
total number 
of seed leaves 








Color and 
total number 
of regular leaves 






) 


Stem color 








Average 
leaf length 








Other 
observations 






{ 



Put all four cartons in a well-lighted place where the 
temperature will be about the same for each. Water the 
plants whenever the soil surface is dry. Put some "plant 
food," such as Hyponex, in each carton once a week. 

Harvesting Your Results 

Look at the plants every two or three days to see how 
they are developing. Do this for about four weeks. Record 
your observations on four charts (like the one shown) so 



you can compare growth under the four light conditions. 

You'll find that the seed leaves are the first two leaves 
that develop. They're easy to recognize because they are 
heart-shaped. They contain food that had been stored in 
the seed, but they also make food like other leaves (see 
"Visit to a Plant Factory," N&S, September 30, 1968). 

Does one group of radishes grow more quickly than the 
others? To find out, figure out the average leaf lengths of 
the four groups from time to time. Do this by measuring 
the lengths of several leaves in one carton. Add together 
all the lengths. Then divide by the number of leaves you 
measured. Your answer is the average leaf length for plants 
grown in that carton. (Be sure to measure leaves from the 
same part of the plants each time.) How do the different 
lighting conditions affect the average leaf length? 

What differences show up when you compare the ob- 
servations you wrote down in the four charts? In what ways 
do all of the plants seem alike? What conclusions can you 
make about the importance of light to radish plants? 

Don't forget to compare the sizes of the radishes them- 
selves, and of the rest of the roots. (When you munch on a 
radish, you're actually eating a root, but it's a special 
kind of root that is mainly stored food. Where did this 
food come from?) ■ 



INVESTIGATIONS 



• Do the growth rates of plants change when the plants' 
surroundings are changed? Make two planters, one that 
light can enter and one that is light-tight. Observe and 
record the growth of the radish plants for one week, 
then reverse the light conditions of the cartons. (Re- 
move the black paper and tape from the light-tight car- 
ton; make the other carton light-tight.) Observe the 
growth for a second week. 

• Change a half-gallon milk container into an "obstacle 
course" for radishes, like the one shown here. Plant 
only two or three seeds in the carton and water the 
plants at least once a week. After three or four weeks, 
observe how the plants have grown in their efforts to 
reach the light. 



about 

IV2 inches 

apart 



OBSTACLE COURSE 
FOR RADISHES 



cutaway view, 
showing obstacles 
inside carton 




After planting, tape 
black paper to sides 
of carton. Then tape 
cardboard rectangles 
inside, as shown. 
Leave the top open. 



December 16, 1968 



; natttr* *nd tcience 



WALL CHART December 16, 1968 



ROUND 




1HE 




■ For thousands of years men have obs i 
moon, our closest neighbor in space, fron 
age distance of 240,000 miles. In the | 
years or so, telescopes have sharpened : 
of the moon's surface— but only of the 
moon that is always facing the earth. In 
few years spacecraft have carried instrun i 
cameras to the moon and sent close-up 
its surface, as well as aerial views of its 
side, back to earth by radio. 

Very soon now, a spacecraft carryii 



1. The Apollo spacecraft, 
carrying three astronauts, 
is launched from Cape 
Kennedy, Florida. The trip 
from the earth to the moon 
and back is expected to 
take about eight days. In 
this period the earth moves 
about 13 million miles in 
its orbit around the sun. 



2. When the first stage of 
the Saturn V rocket has 
burned all its fuel, it drops 
off. The second stage en- 
gines then fire and put the 
third stage and the Apollo 
spacecraft into orbit 
around the earth at a 
speed of about 18,000 
miles an hour. When the 
second stage has burned 
out, it drops off.— 



4. The astronauts then 
flip the command and 
service modules around 
and join them to the LM, 
nose-to-nose. 




3. At the proper time, the 
third-stage engine fires to 
start the spacecraft toward 
the moon. This engine 
boosts Apollo's speed to 
about 25,000 miles an 
hour, fast enough for the 
craft to escape the earth's 
gravitation. 



5. The burned-out 
stage drops away. — 



The command mod- 
ule, with the three astro- 
nauts inside, is slowed 
down by "braking" rock- 
ets. Then it enters the at- 
mosphere and descends by 
parachute to the earth. 



Before the Apollo 
spacecraft enters the 
earth's atmosphere, the 
service module drops 
away. 




travel to the moon, circle it, and return to earth. 
And within a year, if all goes well, men may set 
foot on the moon — the most exciting step of all. 

Three astronauts will leave the earth in the 
three-part Apollo spacecraft, which will be 
launched into space by a three-stage Saturn V 
rocket (see diagram). The rocket and spacecraft 
together will stand 364 feet high — as high as a 
36-story building — on the launching pad. 

This diagram shows the main steps of the trip 
from the earth to the moon's surface and back ■ 



7. Two of the astronauts 
climb into the LM, which 
will complete one orbit 
around the moon. 



The LM links up with 
the command and service 
modules, which have 
turned around for the dock- 
ing, and the two men go in- 
to the command module. 



i modules turn 
that the LM 
ird. As Apollo 
s the moon, 
ol rockets are 
the spacecraft 



li descends to the 
urface. There the 
nauts collect rock 
ral samples, make 
ments, and do 
sntific work. 



Meanwhile, the re- 
ning astronaut circles 
moon in a "parking 
t" in the command and 
'ice modules, and waits 
I the LM completes its 
sion. (While the orbit- 
astronaut is in the line 
ight of the two men on 
moon, he stays in radio 
tact with them.) 



The two astronauts 
blast off in the LM to rejoin 
the command and service 
modules. g£«fl 



Leaving the LM in 
orbit around the moon, the 
command and service 
modules are turned 
around, and rocket en- 
gines are fired to send 
them back to the eart' 








the moon 's approxi- 
mate position in relation to 
the earth when the Apollo 
spacecraft is launched. 
During Apollo's 2 fa-day 
trip to the moon, the moon 
moves about 165,000 
miles in its orbit around 
the earth. 



will carry three as- 
tronauts for most of 
the trip and permit 
them to control their 
flight. 

SERVICE MODULE 

contains scientific 
equipment as well as 
engines for the re- 
turn trip to the earth. 



LUNAR MODULE 
(LM) will carry two 
astronauts to the 
moon's surface and 
back into space. 

THIRD STAGE con 

tains an engine that 
produces 200,000 
pounds of thrust. 




SECOND STAGE con- 
tains five smaller en- 
gines that produce a 
total of one million 
pounds of thrust. 





FIRST STAGE con- 
tains a nest of five 
engines that will de- 
liver a total of 71/2 
million pounds of 
push, or thrust. 









J 




out. nut 




■ When was the last time you made some radio waves? 

Did you say "Never"? The fact is that every time you 
switch an electric light on or off you make radio waves. 

You can test this with a flashlight cell, some copper wire, 
and a radio receiving set. A small portable set works best. 
Scrape the insulating material or coating off the ends of a 
short piece of wire, and tape one end to the flat bottom of 
the flashlight cell. Turn the receiver on as loud as you can, 
then tune out the station, so you hear no sound. Then hold 
the cell close to the set and rub the other end of the wire 
over the metal "button" on the top of the cell. Do you hear 
a noise from the radio? If not, try pressing the taped end of 
the wire tightly against the bottom of the cell as you rub 
the other end over the button. 

The noise you hear, called static, is made by radio waves 
that are detected, or picked up, by the receiver's antenna 
and changed into sound waves by other parts of the set. 
Does your radio transmitter, or sender, make waves while 
electric current is flowing through the wire, or just when 
the current starts or stops flowing? (In finding out, don't 
keep the wire connected to both ends of the cell very long; 
it uses up the cell's electricity too fast.) 

Tracking Radio Waves 

Turn the receiver in different directions as you make 
radio waves. Does this make any difference in the signal — 
the sound that you hear? Probably not, if the receiver has 
a metal rod antenna sticking out of it. But many portable 
radios have an inside antenna— a fine wire coiled around 
a flat iron bar. If the back of the set comes off easily, you 
can probably find this "bar" antenna. Does a bar antenna 
pick up waves better with its long side or with its short end? 
How can you tell? 

Does the transmitter send out waves in all directions? 
You can find out by holding the "best" side of the receiver 
antenna toward the transmitter as you move the receiver 
around the transmitter. What happens to the signal as you 
move the transmitter toward and away from the receiver? 

By taping two or three cells together in series, as shown, 
you can make a battery of cells that produces a stronger 



current. Will a battery like this make stronger radio waves 
than a single cell does? How can you tell? 

Do you think the radio waves come only from the point 
where the wire touches the cell's "button," or from the 
whole wire? Try a longer piece of wire and see if it changes 
the signal in any way. How about the shape and position 
of the wire? You might bend it into a loop, or a square, and 
turn it up-and-down, sideways, and at different angles to 
the receiver. 

What Blocks Radio Waves? 

We know that radio waves, like light waves, can travel 
through a vacuum— a space with nothing in it. Do you think 
they can travel through materials such as wood, metal, 
cloth, glass, plastic, and so on? You can find out by placing 
a piece of such material directly between your transmitter 
and the radio. When you find a solid material that the 
waves pass through, get a container made of that material 
and fill it with sand, soil, water, or other liquids to see 
whether radio waves pass through them. 

Try putting different-sized pieces of the same material 
between the transmitter and receiver and see whether their 
size or thickness seems to affect the signal. Also, try plac- 
ing the same piece of material at different distances be- 
tween the transmitter and receiver. From your findings, do 
you think that radio waves travel only in straight lines, or 
can they "bend" around a small piece of blocking material? 

Can you think of other things that might affect the radio 
waves sent out by your transmitter? How about rain or 
snow, for example? Or trees? Or a brick wall? Use your 
portable radio to look for other sources of radio waves. 
Try an electric razor, a fluorescent lamp. Do they make 
radio waves while they are "on"? As they are switched on 
or off? Docs lightning make radio waves? ■ 




10 



NATURE AND SCIENCE 



These 16-ton statues, toppled from their 

platform at Akivi about 300 years ago, 

were lifted back into place in 1960. 



> * 



M 




, 



* _ 




<w 




V 



O 



f 



V 



Easter Island 



by Carrol Alice Stout 

■ When the stonecarvers had "released" the giant moai 
from the rock atop the dead volcano, the workmen laid 
down their stone picks and returned to their village, about 
four miles across the small Pacific Ocean island. Then the 
12-foot-high moai, or statue, "came to life," walked across 
the island, and climbed onto a stone platform that had 
been built for it near the village. 

That was the story the people on Easter Island (see map) 
told the Norwegian archeologist, Thor Heyerdahl, 10 
years ago when he led an expedition to investigate the 
mysterious stone statues found there. For more than 200 
years, scientists have wondered how the huge statues- 
some weighing as much as 25 tons— had been carved with 
primitive tools and moved across the island. 

The story didn't make sense, though. Statues don't 
"come to life." Besides, as you can see in the photograph 
above, these long-nosed, long-eared, blank-eyed statues 

December 16, 1968 



A Norwegian scientist may have found out 
how these mysterious stone statues were 
carved and set up all over the island 
by people using tools of stone. 



1 


SOU 


rH'^™ 




EASTER 
ISLAND 


lAMI 


:ricaS 


rr?^. 


.• 


1 




'^•s^'N 


PACIFIC 
OCEAN 


r 


/ 1 


'^^"V. 


EASTER ISLAND rano 






A, 

AKIVI 


RARAKU 
1 ' 






1 1 <* ... 

ONE MILE •V—' 



Dots show where statues 

once stood on platforms 

around Easter Island 



with long-fingered hands clasped under their stomachs 
had no legs! 

When the Dutch admiral Jacob Roggeveen "discovered" 
the island on Easter Sunday in 1722, he saw many of these 
statues standing on platforms of stone. Fifty-two years 
later, when the English explorer Captain James Cook vis- 
ited Easter Island, most of the statues lay face down at the 

(Continued on the next page) 

11 



h- 



The "Giants" of Easter Island (continued) 

base of their platforms. Cook also noticed that the people 
qf the island did not seem as lively and healthy as Rogge- 
veen had reported them to be. 

"I Pan Make a Statue" 

When Heyerdahl's expedition got there, no statues were 
standing. For months the scientists and helpers in his ex- 
pedition examined the statues and looked for clues to the 
past. They found that people had lived on the island much 
earlier than most scientists had believed. Wood from a 
statue platform was dated by the carbon- 14 method (see 
"Dating the Past," N&S, September 16, 1968). The test 
showed that the platform had been built sometime between 
900 and 1,300 years ago. 

Almost 300 years ago, according to legends and to clues 
that have been found, a war took place on the island. One 
of the two groups of people who lived on the island was 
wiped out except for one man. This group was known as 
the "long ears" because of their custom of lengthening 
their ear lobes by making holes in them and putting in 
weights. 

Heyerdahl made friends with the island's mayor, Pedro 
Atan. Atan said that he was descended from the only long- 
ear to survive the war, a man named Ororoine. Heyerdahl 
asked Atan if he knew how the statues were carved. 

"Yes," he said. "I will carve you a statue. My relatives 
and I. Only a real long-ear can carve a statue." 



Many people in the camp didn't think that the mayor 
could keep his promise, but Heyerdahl believed him. Late 
the following night, Heyerdahl sat in his tent with two 
companions talking about their work. Suddenly they heard 
a faint humming sound. It was a strange kind of singing. 
It grew louder. Through the tent opening they could see 
men, each with a feathery crown, huddled in a circle in 
the middle of the camp. Each was hitting the ground with 
something he held— a war club, a paddle, or a stone pick. 

Soon two people wearing bird masks could be seen 
dancing to the low-pitched song of the men and the shrill 
voice of an old woman. After the ceremony, when Heyer- 
dahl told the mayor how much he had enjoyed it, the 
mayor said that the ceremony had not been performed to 
entertain the expedition members. The song was for the 
blessing of God, Atua. 

Off to the Quarry 

Next day Atan and five of his relatives took a few ex- 
pedition members to the quarry atop the crater of the dead 
volcano, called Rano Raraku (see map). There, hundreds 
of partly finished statues had remained for centuries since 
an unknown day when the stonecutters had laid down 
their stone picks and never returned (see photo). 

The long-ears began collecting some of the hundreds of 
stone picks scattered over the quarry. The picks looked 
like flat front teeth of some giant animal. The mayor's men 



For at least 300 years these 
finished statues have lain in 
the stone quarry on the side 
of Rano Raraku volcano. 
Others were left standing on 
the side of the volcano (see 
cover). The statues were 
carved out of tuff, a soft rock 
formed of volcanic ash and 
cinders that became consoli- 
dated, or stuck together, as 
rainwater flowed through 
them over many years. 

12 




went right to work. They spread out their picks along the 
base of the rocky wall. Each man set a gourd of water near 
him. The mayor, still wearing his fern leaf crown, mea- 
sured the rock face using his outstretched arms and out- 
spread fingers as a ruler. With a pick he marked the stone. 

The mayor gave a signal, and the men lined up in front 
of the wall and suddenly began singing. They began hit- 
ting the wall in rhythm with the song. It was the first time 
in centuries that the sound of stonecutting had been heard 
at Raraku. One tall old man became so excited that he 
danced as he sang and hit the rock. Slowly, the marks 
grew deeper under the men's picks. 

Without breaking the rhythm, a worker would grab his 
gourd and splash water on the rock to soften it and to 
keep rock splinters from flying into his eyes. 

After they had worked three days, you could see the 
outlines of the statue. Whenever one of the men threw 
aside a dull pick, the mayor grabbed it and struck it against 
another pick on the ground to sharpen it again. 

At the end of the third day the stonecutters stopped. 
They were woodcarvers, and not trained to carve stone 
for long periods of time. Atan said that it probably would 
have taken 1 2 months, with two teams working all day, to 
finish a statue. An archeologist with the expedition 
agreed. But Atan had shown how a huge statue could be 
carved from hard stone using only tools the islanders had 
used centuries ago. 

Can He Raise a Statue? 

Heyerdahl asked the mayor if he also knew how the 
statues were lifted to the platforms. "Of course," said 
Atan. 

Heyerdahl decided to call the man's bluff. He offered to 
pay Atan $100 on the day that the largest statue lying on 
its face in the sand at Anakcna Bay stood again on its 
platform. Right away, the mayor accepted the challenge. 

To raise a statue, Atan needed 1 2 men, three poles, and 
a huge pile of pebbles and boulders. To begin, three men 
put the ends of their poles under the statue and pushed 
down on the other ends, using the poles as levers to lift 
the statue. The figure did not stir. They kept prying. 
Finally, a tiny space could be seen between the ground and 
the statue. The mayor, lying on his stomach beside the 
statue, quickly shoved tiny pebbles under it. Steadily the 
process went on. Lift, push stones under the statue, rest, 
and lift again. Now everyone except the lifters was gather- 
ing rocks. Larger and larger ones were needed as the huge 
figure gradually rose. 

When men could no longer reach the ends of the poles, 
they pulled on ropes fastened to them. Men had to climb 
up the stone pile to place new stones under the statue. One 
false move and the statue and the stones would topple. 

Decembei 16, 1968 



The old woman brought special egg-shaped stones. She 
and the mayor placed them in a circle, thinking their magic 
would help. 

The mayor passed ropes around the stone head and 
fastened them to stakes driven into the ground, to hold the 
statue on the platform. 

After 1 8 days of work, the statue was finally cased into 
an upright position. The pile of stones was taken apart. 

The mayor had done what he said he would do. A 
statue had been lifted to a platform by men using the same 
kind of tools Easter Islanders of long ago might have used. 

How Did the Statues Move? 

Since the mayor had shown that he knew so much about 
statues, Heyerdahl asked whether he knew how they were 

(Continued on the next page) 




Scientists are shown rebuilding the base of the platform to 
which this 22-ton statue was lifted by a giant crane. The 
"top-knot" of red stone is like ones found near each of the 
statues that had been toppled off their platforms. 

13 



The "Giants" of Easter Island (continued) 

moved from Rano Raraku crater, where they were carved, 

to different places around the island. 

The mayor said, "They walked." 

Heyerdahl kept asking and the mayor admitted that 
possibly a miro manga erua — a kind of sledge made out 
of a forked tree trunk— had been used. He knew they were 
used to move heavy stones into position on top of the plat- 
forms. He knew how to make one, but he did not have 
enough relatives to move a statue, and other Easter Island- 
ers were not interested in helping. 

At the camp two large oxen were killed and barbecued. 
Everyone on the island was invited. After the people had 
enjoyed the food and fun of a good picnic, it was not dif- 
ficult to get nearly 200 of them to help move the statue. 

They put the sledge in place under a 12-foot statue that 
had been left long ago on a road. Carefully they lashed 
the statue to the sledge with strong ropes, and pulled the 
giant over the ground. 

In this way, scientists got an idea of how the giant 
statues may have been carved, carried across the island, 
and raised to their platforms. Why they were made is 
another question. Present-day islanders believe that the 
statues represented ancestors of the people who made 
them, and that those people thought the statues had 
"supernatural" powers. 

The statues are not the only remains found on the island. 
There are many elevated tombs, hundreds of stone towers 
that must have marked land boundaries, caves lined with 
stones fitted together, rocks with pictures carved into their 
sides, and the remains of stone houses and farmyards. 




Writing like this is carved on wooden tablets found on Easter 
Island. It might reveal something about the religion of the 
people who carved the giant stone statues— but so far no one 
has been able to decipher the writing. 

There are also wooden tablets carved with a writing like 
no other writing known today (see photo). 

These accomplishments seem astonishing to Dr. William 
Mulloy, a Professor of Anthropology at the University of 

14 




This head of an Easter Island moai was displayed in front of 
the Seagram Building in New York City last month, before 
being shown in other large cities in a campaign to raise 
money to restore more of the statues on the island. 

Wyoming, at Laramie. (An anthropologist is a scientist 
who studies how man has developed.) Dr. Mulloy has 
been studying the remains on Easter Island for 13 years, 
and is now directing efforts to restore many of the giant 
statues to their platforms. 

He believes that the small island could never have had 
more than three or four thousand people living on it. And 
he doubts that many visitors could have reached the re- 
mote island bringing new ideas with them. Yet the island 
people must have developed a fairly complicated way of 
living to produce the things they did before war almost 
wiped them out. 

By studying the remains left by these people, scientists 
may learn more about how they lived, worked, played, and 
worshiped. But unless someone finds the "key" to the 
writing on the tablets and learns to read their messages, 
the mystery of Easter Island may remain at least partly 
unsolved ■ 

NATURE AND SCIENCE 



b- 



■ ii11 "-" 1 " 



HOW FAST 
DOES THE 

WIND BLOW? 



■ When the' wind blows so hard that you can barely make 
headway walking into it, how fast is the air moving? You 
can measure the speed of the wind on breezy days as well 
as gusty ones by making a simple anemometer, or wind 
gauge. 

To make an anemometer, you will heed a milk carton 
with both ends removed, a long darning needle, two 
shorter needles, a cork, and a piece of cardboard. Thd 
carton should be thumbtacked to a block of wood. Cut 
the middle section of one side of the carton as shown here, 
and fold up flaps A and B to make supports for the axle. 



- zr 

-2T - 



SIDE 
VIEW 




NEEDLE JCOR 
POINTER -► / 



BEAUFORT SCALE 

WHEN— WIND SPEED IS— 

Smoke rises straight up mph 

Smoke drifts in one direction 1-3 mph 

Leaves rustle; flags stir 4-7 mph 

Leaves and twigs move constantly 8-12 mph 

Paper, small branches move; flags flap 13-18 mph 

Small trees sway; flags ripple 19-24 mph 

Large branches move; flags beat 25-3 1 mph 

Whole trees move; flags are extended 32-38 mph 

Twigs break off trees; walking is difficult 39-46 mph 



Push the long needle through the flaps, placing a cork 
at the center (see diagram). Mount one needle vertically 
in the cork to serve as a pointer. Cut a square of card- 
board td fit inside the carton, attach the third needle to it 
with tape, and stick the needle into the cork as shown. 
When the apparatus is set up, the card should move quite 
easily arid smoothly within the box. (You may have to 
adjust the cork and axle.) 

When the wind is blowing, point the apparatus into the 
wind so that the wind blows through the box. As the wind 
pushes against the cardboard square, it turns the axle and 
deflects or tilts, the needle pointer. 

The distance the needle is tilted indicates how fast the 
wind is flowing through the carton. To measure this dis- 
tance, you need a gauge. Fasten a piece of cardboard to 
the side of the carton and draw a line on it parallel to the 
indicator needle when it is standing straight up. 

You can calibrate the gauge, or mark the tilt of the 
needle at different wind speeds, by using the Beaufort 
scale on this page. — franklyn m. branley 

December 16, 1968 



-investigation- 



do the speed and direction of the wind give any clues 
about changes of weather where you live? You can find 
out by keeping a record on a chart like the one shown 
here. Each day at the same time, say about 8 o'clock in 
the morning, measure the wind speed and direction from 
which it is coming. About six hours later, note the weather 
(sunny, cloudy, rainy, snowy, or whatever) and enter it 
oh the chart. 



DATE 


TIME 


WIND 
SPEED 


WIND 
DIRECTION 


TIME 


WEATHER 



























When you have kept the chart for several weeks, study 
it to see if there is any connection between the speed and 
direction of the wind and the weather that follows. Keep 
in mind that your findings would be mdre reliable if your 
anemometer were more exact, and if you measured the 
wind hourly for months, instead of once a day for several 
weeks. Also, that wind is only one of the things that helps 
make the weather what it is. 



15 



WHAT'S 
NEW 

by 

B. J. Menges 




Fog over airports is a serious prob- 
lem to aviation, second only to over- 
crowding of the skies and runways. 
Cold-weather fog can be removed by 
"seeding" it with dry ice, which turns 
droplets of water into falling snow. But 
this method doesn't work with the 
much more common fog that forms at 
temperatures above freezing — the fog 
that is blown in from the sea or that rises 
from warm ground. 

A promising solution is a new device 
called Fog-Sweep. This machine blows 
two chemicals into the fog through a 
giant plastic tube. One chemical charges 
the water droplets in the air with elec- 
tricity, so they attract each other and 
combine (see "The Physics of Fasteners," 
N&S, December 2, 1968 ). The second 
chemical helps them combine faster, by 
weakening the elastic "skin" that holds 
each droplet together (see "What Makes 
a Drop?", N&S, October 14, 1968). The 
combined droplets are heavy enough to 
fall as rain. 

"Dead" volcanoes could erupt in 

the United States at any time, says the 
head of the government's Geological 
Survey, Dr. William T. Pecora. He warns 



that we shouldn't assume that a volcano 
is "dead" simply because it hasn't 
erupted for hundreds or thousands of 
years. (See "Kilauea Blows its Cool," 
N&S, October 28, 1968.) So-called 
"dead" volcanoes erupted in Costa Rica 
and Iran last summer, with great loss of 
life and property. 

Dr. Pecora says that a number of vol- 
canoes in the western states have "erup- 
tion potential," including Mount Rainier 
and Mount St. Helens in Washington, 
and Mount Lassen and Mount Shasta in 
California. He urges that a network of 
detection instruments be set up in these 
mountains to pick up early signs of vol- 
canic activity. Nearby residents could 
then be warned of any danger. 

If you get chilled and wet playing 
outdoors while your friend goes to the 
movies, which one of you is more likely 
to catch cold? Surprisingly, your friend. 
Recent experiments at Baylor University 
in Waco, Texas, tested the don't-get- 
your-feet-wet theory on a group of 
healthy men. Some were exposed to cold 
and dampness, others to viruses that 
cause colds, still others to both, and some 
to neither. The result: exposure to cold 
and dampness didn't increase the num- 
ber or the severity of colds. Why, then, 
are colds most common in winter? Be- 
cause people spend more time indoors, 
in close contact with each other. Here, 
cold viruses are spread easily by a cough 
or a sneeze. 

An alligator purse or belt is noth- 
ing to be proud of. Alligators are being 
killed so fast that they are in danger of 
being wiped out. If an item is made of 
genuine alligator, not crocodile, the skin 
probably was obtained illegally. Except 
for a small species found in Communist 
China, the only true alligators in the 
world today occur in the southern United 



States. In almost every one of these 
states, alligator hunting is illegal. Yet 
poachers continue to kill alligators under 
cover of darkness, even in Everglades 
National Park. They often earn as much 
as $700 a night. If caught and found 
guilty, they receive small fines or short 
jail terms that they consider "business 
expenses." 

Until recently, large alligators were 
abundant in the South; now few survive 
to reach breeding size. Stronger laws and 
law enforcement are urgently needed to 
save this awesome animal that has ex- 
isted since the time of the dinosaurs. 
Perhaps the answer might be a law for- 
bidding the sale of any alligator goods. 

Mysterious radio signals from 
space have puzzled scientists since their 
discovery earlier this year. At that time 
the signals were found to come from one 
point in space. Their unknown source 
was called a pulsar because the signals 
came in pulses. Ten more pulsars have 
since been discovered elsewhere in space. 

Some stars and planets are known to 
send out radio signals; but unlike these 
signals, pulsar signals are repeated reg- 
ularly with exactly the same timing. 
This has led some scientists to wonder 
whether the signals were coming from 
intelligent beings in space. Most, though, 
have thought that the signals were being 
produced by ancient, burned-out stars 
called white dwarfs. Now Dr. Frank D. 
Drake of Cornell University, in Ithaca, 
New York, says the pulsar signal pattern 
could be produced only by neutron stars. 
These are stars that have collapsed and 
become so dense that a one-inch cube 
taken from one of them would weigh 
millions of tons on earth. Scientists have 
talked about neutron stars for 30 years, 
but have never been able to prove they 
exist. The pulsar signals may furnish that 
proof. 



An artist's drawing shows how a Deep 
Submergence Search Vehicle being de- 
signed for the United States Navy is ex- 
pected to look and work. The deep-sea 
craft being developed by the Lockheed 
Missiles and Space Company will be able 
to explore the ocean floor and recover 
small objects at depths of 20,000 feet. 

16 




Using This Issue... 

(continued from page 2T) 

set on the map over "your school." 
Tune the set to a station whose signal 
it receives clearly, and be sure to re- 
cord the call letters of the station for 
later checking. Then turn the volume 
down until you can just barely hear 
the signal. 

Have a pupil rotate the set slowly 
around the spot on the map where it 
is resting, listening carefully to find the 
position where the sound is weakest. 
If the sound is lost altogether, turn the 
volume up until you can just barely 
hear it again. 

When the signal is least loud, one 
end of the antenna is pointing toward 
the transmitter. Draw a straight line 
through the school mark on the map 
in the direction in which the ends of 
the receiver antenna are pointing. The 
transmitter must be somewhere along 
that line, but it could be in either direc- 
tion from the receiver (see diagram). 

To locate the transmitter, you will 
have to move the map and receiver to 
a place at least a few blocks to one side 
or the other of the line drawn on the 
map. Mark the new location on the 
map, place the receiver on it, tune in 
the same station, and take another 
"reading." The line you draw on the 
map through your second location 
should cross the line drawn through 
the school marker, and the transmitter 
should be near the point on the map 
i where the lines cross. You can tele- 
phone the radio station to find out ex- 
actly where its transmitter is located. 

Brain-Boosters 

Mystery Photo. The icicle formed 
under the roof of the house, where the 



wire is attached. When the weather be- 
came warmer, the icicle broke away 
from the roof and slid down the wire. 

You might challenge your pupils to 
explain how icicles form under the 
eaves of a house. What often happens 
is this: Heat from inside the house 
melts the underside of the layer of 
snow that has accumulated on the roof. 
The meltwater trickles down the roof 
until it reaches the eaves, which are 
not in contact with the main part of 
the house, and don't get much of its 
heat. The air temperature under the 
eaves may be low enough to freeze the 
water and make icicles. 

What would happen if? Let the pu- 
pils try to guess the order in which the 
blocks will slide off before you make 
a demonstration (if possible) with a 
lazy susan or a record player from 
which the spindle can be removed. 

Blocks 1 and 3 will slide off because 
of the centrifugal effect of the turn- 
table's spinning motion. Since block 3 
is located farther from the center of 
the turntable than block 1 , it is revolv- 
ing around the center faster than block 
1, so the centrifugal effect on it is 
greater. Thus, block 3 will slide off 
first, followed by block 1 . If block 2 is 
precisely over the center of the turn- 
table, then it is rotating around its own 
axis (rather than revolving around the 
center of the turntable), and it will 
never slide off. 

Can you do it? If your pupils tried 
the investigations and projects in 
"What's in a Drop?" and " 'Surfing' to 
Safety," N&S, Oct. 14, 1968, pages 
13-15, they will know that it is im- 
possible to rest a needle on the surface 
of soapy water, because soap weakens 
the "skin" effect produced by surface 
tension. (See also page 3T of that 
issue.) 



\ bar antenna (A) de- 
tects radio waves 
jeast well when one 
bf its ends is pointing 
toward the transmit- 
ter. Your pupils can 
jse a bar-antenna 
eceiver at two loca- 
tions to locate the 
transmitter on a map 
(see text). 

December 16, 1968 




Fun with numbers and shapes. You 

might want to let the class try to solve 
this problem in the schoolyard. All you 
will need is a piece of chalk and a 
long, straight stick. First draw a line 
to represent the part of the ditch that 
is already dug; then let the children 
take over. 

The diagram shows a way to solve 
the problem. First draw two equal lines 
(A in diagram) at right angles to the 




ditch. Connect the ends of the lines 
with a long line (B) that goes past the 
corner of the house. Then draw two 
lines (C) that are at right angles to line 
B and are the same length as lines A. 
Draw a line (D) through the ends of 
lines C to mark the place where the rest 
of the ditch should be dug. 

The class will probably need some 
help in finding this solution. Or per- 
haps they will find another way to help 
the builders complete the ditch. 

For science experts only. The posi- 
tion of the fly in the train car will not 
change noticeably when the train stops. 
This is because the fly is "cushioned" 
by the air, which comes to a gradual 
stop with the train. 

A more massive object, such as a 
person, tends to move forward in the 
car as a train slows down, because his 
greater mass gives him a momentum 
great enough to overcome the resist- 
ance of the air. If a person were swim- 
ming in a railroad car full of water, 
which would offer more resistance to 
his motion than air offers, his position 
in the car would not change very much 
as the train stopped. 

Just for fun. Perhaps your pupils 
might like to find out which does a 
better job of cleaning pennies— catsup, 
or a salt-and-vinegar mixture. They 
could also find out what other common 
foods can clean pennies. Anything 
made from tomatoes, for example, will 
clean pennies (or other copper objects). 

3T 



** 



Books That Will Help You . . . 

(continued from page IT) 

bibliographic references for each ex- 
perience. Two other features of the book, 
included in each chapter, are the sec- 
tions "Other Possible Experiences With 
" and introduction to the Ex- 
perience to Follow." 

The appendix includes "A Suggested 
Order for the Use of the Stories" and 
"Desert Adaptation of the Materials." 
The sequence of experiences is: sand, 
earthworm, robin, cat, tree, woodpecker, 
spiders, moles and shrews, ants, grass, 
garden, bees, caterpillars and butterflies, 
grasshoppers or crickets. Illustrations are 
included that can be helpful and enjoy- 
able to even the youngest children. 

Science for the Elementary School, by 

Edward Victor (Macmillan Company, 
1965, 772 pp., $8.95). Although Part One 
of this book has some worthwhile chap- 
ters on the broad goals of the elementary 
science program, methods of teaching 
science, sources of science materials, and 
evaluation of science learning, it is Part 
Two, with its science content, learning 
activities, and bibliography, that will be 
of particular usefulness to many teachers. 
The science content is presented in 
outline form, simply and clearly, yet with 
sufficient detail. This format should help 
teachers by: 

1 ) lending itself to the presentation of 
concepts in a logical learning sequence; 

2) eliminating extraneous material to 
make key concepts clearly and easily 
identifiable; 

3) making it easier for teachers to 
select concepts for use at different grade 
levels; 

4) simplifying the wording and mak- 
ing it easier for teachers to bring the 
vocabulary down to an appropriate level 
while preserving the accuracy and flavor 
of the science content; 

5) being sufficiently detailed to pro- 
vide the teacher with ample material for 
daily lessons and unit plans. (In fact, 
more science content has been included 
than is usually taught in grades K-6. The 
additional material is intended for the 
fast learner.) 

The learning activities that follow the 
science content in each chapter are not 
all-inclusive Their purpose is to familiar- 
ize teachers with one representative activ- 
ity that can be used to teach each of the 
key concepts in the outline. The topics 
covered in the outline are "The Earth and 
the Universe," "Living Things," and 
" Matter and Energy." 




charts 



Prepared under the 
supervision of The 
American Museum 
of Natural History 



from 
nature and science 



Let your classroom walls help you teach with a completely new set of 10 Na- 
ture and Science Wall Charts. Reproduced from the pages of Nature and 
Science— and enlarged 300% in area— these Wall Charts cover a range of sub- 
jects that your science class should know about. 

For chalkboard, bulletin board, wall— for science exhibitions and displays— 
here are lasting sources of information that are always ready to catch (and 
educate) the wandering eye of any student. 



* all fully illustrated in vivid color 

* printed on durable, quality stock 

* each chart an abundant 22 by 34 inches 

* delivered in mailing tube for protection and storage 



Six Ways to Success — describes six 
ways in which plants and animals are 
adapted to insure survival of the species. 

Travel Guide to the Sun and Its Planets 

— depicts our solar system, showing rel- 
ative sizes of the planets, number of 
satellites, temperature, diameter, dis- 
tance from sun. 

The "Spirit" That Moves Things — ex- 
plains what energy is, where it comes 
from, and how it can change form. 

History in the Rocks — cross section of 
Grand Canyon shows how each geo- 
logical stratum was formed and illus- 
trates some representative fossils from 
each period. 

Spreading the Word — depicts how man 
has communicated information from 
one place to another through the ages. 



Visit to a Plant Factory — shows how 
green plants make their own food and 
how the food is transported to their 
parts. 

Rabbit Rollercoaster — illustrates the 
annual population cycle of the cotton- 
tail and describes why few rabbits live 
as long as a year. 

How Diseases Get Around — diagrams 
ways in which diseases arc spread and 
shows how vaccines protect against 
disease. 

Who Eats Whom — explains the ecol- 
ogy of the sea and some of the links in 
its "food chains." 

The Horse's First 55 Million Years — 

museum reconstructions in a time-line 
presentation illustrate the evolution of 
the horse. 



Imagine your pupils' excitement as you display a different chart each month 
of the school year. Order a complete collection of ten for only $7.50. 

To order, use postpaid order form bound into this issue. 



4T 



NATURE AND SCIENCE 



nature and science 

TEACHER'S EDITION 

VOL. 6 NO. 8 / JANUARY 6, 1969 / SECTION 1 OF TWO SECTIONS 

COPYRIGHT © 1968 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 

4 N & S REVIEWS ► 

Books That Will Help You 
Teach Science 

by Dulcie I. Blume 

This is the last of three reviews of some books published in the past five 
years that have earned a front-row position on the shelves of elementary 
school teachers of science. Many were written by people with years of ex- 
perience in teaching science to children. All of these books will help you to 
answer questions . . . to develop and direct investigative activities . . . to create 
classroom situations from which your pupils will be propelled to their own 
investigations, observations, and books. 



nature 
and science 



Science Equipment in the Elementary 
School (University of Colorado — Ele- 
mentary Science Advisory Center, Boul- 
der, Colorado, March 1967, 36 pp., $1). 
This bulletin contains a long list of ma- 
terials for teaching elementary school 
science, along with photographs and 
suggestions for use. The list is organized 
into rough categories for convenience, 
but many items could be put into several 
categories. The classroom was chosen as 
the unit for estimating quantities. Some 
indication of cost is given wherever pos- 
sible. 

There is also a special "junk" category: 
gear wheels, spools, pastry cutters, bottle 
caps, bicycle pump, corks, sponges, etc. 
The one feature these objects have in 
common is that they cost "nothing," be- 
ing brought in by the children or teacher. 
But they are invaluable: a good labora- 
tory, whether in university or elementary 
school, always has an ample junk box. 

The following bulletins come from the 
National Science Teachers Association of 
the National Education Association, and 
may be ordered from NEA Publications 
Sales Division, 1201 16th St., N.W., 
Washington, D.C. 20036. 

Biological Science — Teaching Tips 
from TST (1967, 224 pp., $5, Stock 



Mrs. Dulcie I. Blume is Coordinator of Cur- 
riculum Materials of the Alameda County 
School Department, Hayward, California. 



Number 471-14526); Earth-Space 
Science — Teaching Tips from TST 

(1967, 121 pp., $4, Stock Number 471- 
14350); Physical Science — Teaching 
Tips from TST (1967, 144 pp., $5, Stock 
Number 471-14348). These three bul- 
letins are compilations of articles from 
The Science Teacher. The articles fall 
into two categories — those with content 
information to enrich the teacher's back- 
ground, and those containing classroom 
ideas that can help add variety to a 
science program. The content may be 
familiar to some, but most of the articles 
present new information not commonly 
available to the secondary teacher. 

Helping Children Learn Science ( 1 966, 

188 pp., $3, Stock Number 471-14498). 
This bulletin is a compilation of articles 
from the periodical Science and Children, 
for the elementary school teacher. The 
compilers had in mind articles that (1) 
present material that is consistent with 
accepted philosophy and practices and 
with the latest trends in science educa- 
tion; (2) provide usable material for 
classroom teachers, curriculum person- 
nel, and administrators who are not 
science specialists. 

The articles are presented in five cate- 
gories: objectives for teaching science, 
background information for the teacher 
of science, resources for teaching-learn- 
ing, classroom teaching-learning experi- 
ences, and experimental science curricu- 
lum studies. Just one excellent example 
(Continued on page 4T) 




IN THIS ISSUE 

(For classroom use of articles pre- 
ceded by • . see pages 2T-4T.) 

Tracing Prehistoric Trade 

How archeologists found a way to 
prove that men's early villages 
traded with each other. 

• Exploring Winter Ice 

Your pupils can investigate how ice 
forms and melts on a lake or pond, 
and test their findings in a refrigera- 
tor "laboratory." 

• Tales Told by Trails 

By learning to "read" the tracks of 
wild mammals, your pupils can study 
their travels and behavior. 

Who Goes There? 

This Wall Chart shows how to 
identify the tracks of common ani- 
mals. 

• Brain-Boosters 

How Do Turtles Find the Sea? 
A biologist tells of his efforts to find 
out how baby turtles find their way 
to the ocean and where they go when 
they get there. 

• A Swinging Experiment 

Your pupils can use a simple pen- 
dulum to test the idea that objects 
of different weight dropped simul- 
taneously from the same height will 
land at the same time. 



IN THE NEXT ISSUE 

A special-topic issue: Life in the 
Arctic: How animals are adapted to 
survive in the Arctic . . . The Eski- 
mo's world . . . Cycles in animal pop- 
ulations . . . How biologists are 
studying polar bears . . . Learning to 
live with permafrost. 



USING THIS 

ISSUE OF 

NATURE AND SCIENCE 

IN YOUR 

CLASSROOM 



Exploring Winter Ice 

Here are answers to the questions 
about photos in the article: 

Page 4: A lake freezes and unfreezes 
first at the shore. When the shoreline 
is free of ice while the rest of the lake 
is frozen, the lake must be unfreezing. 
. . . When water that has collected in a 
deep crack in a rock is subjected to 
freezing temperatures, a layer of ice 
forms at the surface of the water. With 
more cold weather, the rest of the 
water may freeze. The expanding ice, 
trapped between the rock and the ice 
layer above, pushes against the sides 
of the crack. In the course of many 
freezings and meltings it may gradually 
split the rock. 

Page 5: The constant movement of 
water in the river channel keeps it from 
freezing. . . . The movement of the 
birds stirs up the water, so it can't 
freeze, and the birds continue to flock 
to this "oasis" in the frozen lake, keep- 
ing it unfrozen. . . . Air bubbles were 
trapped in the block of ice as it froze. 

Page 6: Like the soil and rocks on 
the shore, the wooden pilings take heat 
from the water on cold days, making 



it freeze around them first. They lose 
heat to the ice on warm days, making 
it melt there first. The repeated freez- 
ing and melting of ice around the pil- 
ings prevents a thick layer of ice from 
building up around them, so the ice 
around the pilings is always "new." or 
clear, ice. The ice looks black because 
you can see through it to the dark 
water below. 

Tales Told by Trails 

Most wild mammals are shy or noc- 
turnal, so their behavior is difficult to 
observe. We can interpret it by follow- 
ing tracks and other signs. Unless chil- 
dren get outdoors and look, the study 
of wild mammals will be largely book 
lessons. 

Have your pupils discuss places in 
your area where mammal signs are 
likely to show up. Proceed with the 
observations on an individual basis. 
Advise using a portrait attachment for 
snapshots of small tracks. Encourage 
pupils to bring in sticks showing tooth- 
marks, nuts and acorns that have been 
gnawed open, and casts of tracks. 

Casts of animal tracks in mud or 
ice are easily made by pouring a mix- 
ture of plaster of Paris and water into 
the track. If the children practice mix- 
ing plaster of Paris in school, they will 
have no difficulty on the trail. Use 
quick-setting plaster, available at hard- 
ware stores. Add enough plaster to fill 
the track, a little at a time, to Vi cup 
of water in a tin can or plastic con- 
tainer. When the mixture looks like 
pancake batter, pour it into the track 



(see diagrams). A very neat job results 
from placing a stiff paper collar fast- 
ened with a paper clip around the 
track. The plaster may be lifted off 
after setting for about 15 minutes. Any 
mud can be cleaned off with an old 
toothbrush at home. 

If the air is very cold, casts can be 
made in snow by spraying the track 
with water from an atomizer. This will 
harden the track. As a further pre- 
caution against melting, mix some 
snow into the wet plaster. 

This cast will be a "negative" repro- 
duction of the track; that is, the paw 
marks will protrude. To make a "posi- 
tive" cast, first coat the negative cast 
with vaseline, then set it in the paper 
collar and pour plaster mixture over it 
until the protruding paw mark is cov- 
ered. When the plaster has set, you can 
separate the positive cast of the track 
from the negative cast. If the negative 
is removed carefully each time, many 
positives can be made from it. 

A Swinging Experiment 

Some of your pupils may "know" 
that a 100-pound ball and a 1 -pound 
ball dropped simultaneously from the 
same height will reach the ground at 
the same time. They will probably say 
that "Galileo proved it by dropping 
balls of different weight from the 
Tower of Pisa." There is no historical 
evidence that Galileo ever did that 
experiment, although it was done in 
Galileo's time at another tower by a 
Dutch mathematician named Stevinus. 
(Continued on page 3T) 



POSITIVE 




MAKING PLASTER TRACK CASTS 



RUBBER BAND 



NATURE AND SCIENCE is published for The American 
Museum of Natural History by The Natural History 
Press, a division of Doubleday & Company, Inc., fort- 
nightly September, October, December through March; 
monthly November, April, May, July (special issue). 
Second Class postage paid at Garden City, N.Y. and at 
additional office. Copyright & 1968 The American 
Museum of Natural History. All Rights Reserved. Printed 
in U.S.A. Editorial Office: The American Museum of 
Natural History, Central Park West at 79th Street. 
New York, N.Y. 10024. 

SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester 
per pupil, $1.95 per school year (16 issues) in quanti- 
ties of 10 or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's 
edition $5.50 per school year. Single subscription per 
calendar year (17 issues) $3.75. two years $6. Single 
copy 30 cents. In CANADA $1.25 per semester per 
pupil, $2.15 per school year in quantities of 10 or more 
subscriptions to the same address. Teacher's Edition 
$6.30 per school year. Single subscriptions per cal- 
endar year $4.25, two years $7. ADDRESS SUBSCRIP- 
TION correspondence to: NATURE AND SCIENCE, The 
Natural History Press, Garden City. N.Y. 11530. Send 
notice of undelivered copies on Form 3579 to: NATURE 
AND SCIENCE. The Natural History Press, Garden City, 
N.Y. 11530. 



2T 



N ATI' HI' [\l> S< U:\CE 




VOL. 6 NO. 8 / JANUARY 6, 1969 



and scie 




e 



that animals "write" in the 
snow. 

see page 7 

TALES TOLD BY TRAILS 



How did 

these "ice 

lushrooms" 

form on 
he stream? 



s why does ice form 
first around plant 
stems? 



What made tl"« 
the »ake ice? 



kJk 



rtat ura and science 

VOL. 6 NO. 8 / JANUARY 6, 1969 
CONTENTS 

2 Tracing Prehistoric Trade 

4 Exploring Winter Ice, by David Webster 

7 Tales Told by Trails, by Dave Mech 

8 Who Goes There? 

1 1 Brain-Boosters, by David Webster 

1 2 How Do Turtles Find the Sea?, 

by Archie Carr 

15A Swinging Experiment 

1 6 What's New?, by B. J. Menges 






PICTURE CREDITS: Cover, pp. 4-6, 11 (except p. 5 bottom), photos by David 
Webster; p. 3, map adapted from "Obsidian and the Origins of Trade," by 
J. E. Dixon. J. R. Cann. and Colin Renfrew. Copyright © 1968 by Scientific 
American, Inc. All rights reserved. Left photo from The American Museum of 
Natural History, right photo from University of Pennsylvania Museum; p. 5, 
bottom. Education Development Center; pp. 7-11, 14-16, drawings by Graphic 
Arts Department, AMNH; p. 10, photo by Dave Mech; pp. 12, 14, photos by Jo 
Conner; p. 13, Archie Carr; p. 15, photo from Science Photo/Graphics, Ltd. 




PUBLISHED FOR 

THE AMERICAN MUSEUM OF NATURAL HISTORY 

BY THE NATURAL HISTORY PRESS 

A DIVISION OF DOUBLEDAY & COMPANY, INC. 

editor-in-chief Franklyn K. Lauden; executive editor Laurence P. 
Pringle; associate editor R. J. Lefkowitz; assistant editors Mar- 
garet E. Bailey, Susan J. Wemert; editorial assistant Alison New- 
house; art director Joseph M. Sedacca; associate art director 
Donald B. Clausen • consulting editor Roy A. Gallant 

publisher James K. Page, Jr.; circulation director J. D. Broderick 
promotion director Elizabeth Connor 
subscription service Frank Burkholder 

NATIONAL BOARD OF EDITORS 

PAUL F. BRANDWEIN, CHAIRMAN, Dir. of Research, Center for Study of 
Instruction in the Sciences and Social Sciences, Harcourt, Brace & World, Inc. 
J. MYRON ATKIN, Co-Dir., Elementary-School Science Project, University of 
Illinois. THOMAS G. AYLESWORTH, Editor, Books for Young Readers, 
Doubleday & Company, Inc. DONALD BARR, Headmaster, The Dalton 
Schools, New York City. RAYMOND E. BARRETT, Dir. of Education, Oregon 
Museum of Science and Industry. MARY BI.ATT HARBECK, Science Teach- 
ing Center, University of Maryland. ELIZABETH HONE, Prof, of Education, 
San Fernando (Calif.) State College. GERARD PIEL, Publisher, Scientific 
American. SAMUEL SCHENBERG, Dir. of Science, New York City Board of 
Education. WILLIAM P. SCHREINER, Coord, of Science, Parma (Ohio) City 
Schools. VIRGINIA SORENSON, Elementary Science Consultant, Dallas In- 
dependent School System. DAVID WEBSTER, Staff Teacher, Elementary 
Science Study, Educational Development Center. Newton, Mass. • REPRE- 
SENTING THE AMERICAN MUSEUM OF NATURAL HISTORY: FRANK- 
LYN M. BRANLEY, Chmn., The American Museum-Hayden Planetarium. 
RICHARD S. CASEBEER, Chmn., Dept. of Education. THOMAS D. NICH- 
OLSON. Asst. Dir., AMNH. GORDON R. REEKIE, Chmn., Dept. of Exhibi- 
tion and Graphic Arts. DONN E. ROSEN, Chmn., Dept. of Ichthyology. 
HARRY L. SHAPIRO, Curator of Physical Anthropology. 

NATURE AND SCIENCE is published for The American Museum of Natural History by 
The Natural History Press, a division of Doubleday & Company, Inc., fortnightly 
September, October, December through March, monthly November, April, May, July 
(special issue). Second Class postage paid at Garden City, N.Y. and at additional 
office. Copyright © 1968 The American Museum of Natural History. All Rights Re- 
served. Printed in U.S.A. Editorial Office: The American Museum of Natural History, 
Central Park West at 79th Street, New York, N.Y. 10024. 

SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester per pupil, $1.95 per school 
year (16 issues) in quantities of 10 or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's edition $5.50 per school year. 
Single subscription per calendar year (17 issues) $3.75, two years $6. Single copy 30 
cents. In CANADA $1.25 per semester per pupil, $2.15 per school year in quantities 
of 10 or more subscriptions to the same address. Teacher's Edition $6.30 per school 
year. Single subscriptions per calendar year $4.25, two years $7. ADDRESS SUB- 
SCRIPTION correspondence to: NATURE AND SCIENCE, The Natural History Press, 
Garden City, N.Y. 11530. Send notice of undelivered copies on Form 3579 to: 
NATURE AND SCIENCE, The Natural History Press, Garden City, N.Y. 11530. 



■ The remains of some of the earliest villages formed 
men have been dug up in recent years by archeologis 
scientists who study how people lived in the past. The 
villages were scattered about in the lands around t 
eastern end of the Mediterranean Sea (see map). 

When the remains were "dated" by the carbon- 
method (see "Dating the Past," N&S, September 16, 196i 
they showed that people were living in some of the villajj 
as early as about 10,000 years ago. This was about 3,0< 
years before writing was invented, so the villagers left i 
written records that might tell how they lived. 

At the sites of the villages, however, archeologists foui 
the remains of simple gardening tools, pieces of grain, ai 
the fossil bones and horns of sheep and goats. Some 
the goat horns were straight, like those of wild goats, ai 
some were twisted, like those of today's domestical 
goats. This showed that the early villagers had begun 
raise food plants— and perhaps even animals— in additii 
to getting food from wild plants and animals, as their a 
cestors had done for thousands of years. 

The Question of Trade 

Archeologists wondered, though, whether the people 
these ancient villages traded goods with each other 
whether they even knew that other villages existed. At 
all, the villages were hundreds of miles apart, and ma 
were separated by mountains or water. 

At the sites of the ancient villages, archeologists fou 
the remains of clay pots and of cutting tools made of c 
sidian, a hard volcanic glass that can be chipped li 

NATURE AND SCIENCE 




NEMRUTDAfiO 

Obingol 

Qayonu 

♦ o 



OCIFTLIK 
Catal Huyuk 

• ♦ 
Mersin 
• O 




Tell Al-Judaidah 
O 

Ras Shamra 
O 



Tell Shemsharah 

♦ 

Matarrah 

o 



Jarmo 
♦O 
Sarab 
♦O 



Bouqras 
♦ O 



Tepe Gawra 



C2ZZ23 



CYPRUS 



Khirokitia 
O 



MEDITERRANEAN SEA 



MILES 



Byblos 



Tell Ramad 
OO 

Jericho 
O 



Beidha 
O 



Tepe Guran 
♦ O 

Ali Kosh 
♦ O 



100 



200 



300 



400 



'int to sharpen an edge. The pottery and the tools found 
K the different villages had all been made in much the 
'ime way, but that didn't prove that the people of the 
llages were in contact with each other. They might have 
lade these simple objects the same way by chance. 
1 It seemed likely that there was some trading between 
'llages, though, because some of the villages were hun- 
'eds of miles from places where obsidian is found, around 
olcanoes. Three British archeologists decided to try to 
fad a way to tell where the obsidian found in each village 
ime from. They described their investigation in an article 
! iblished recently in Scientific American magazine. 

jie Obsidian Test 

i The scientists analyzed samples of obsidian taken from 
Afferent volcanic areas. They found that obsidian from 
le same place contained the same amounts of the ele- 
ments barium and zirconium, while obsidian from differ- 



This map shows the sites ( ) of ancient villages 
in the Near East which scientists believe were 
trading with each other as early as about 10,000 
years ago. The signs (♦ o • O ) under a 
village name show which types of obsidian were 
found in tools dug up there. The larger signs 
( ♦ O • O ) show where each type of obsid- 
ian is found on or near the surface of the earth. 
The obsidian used in some villages must have 
come from at least 400 miles away. 



ent sources had different amounts of these elements. 

Next they located places of volcanic activity nearest 
to the early villages, where the people could have found 
obsidian. They measured the amounts of barium and 
zirconium in the obsidian from each of those places and 
in the obsidian tools found at the village sites. This made 
it possible for them to figure out where the obsidian found 
at each site had come from originally. By matching the 
obsidian sources and the villages where the obsidian tools 
were found, the scientists found that obsidian had been 
carried across mountains, deserts, and water to the early 
settlements (see map). 

Now the scientists had proof that the ancient village- 
dwellers had traded with each other. But that's not all. 
Their discovery of a way to trace obsidian found in one 
place to the place where it was formed may help arche- 
ologists find answers to other questions about the travels 
of prehistoric men ■ 




Obsidian splits along 
curved surfaces (see 
photo), so it is easily 
chipped to form a hard, 
sharp cutting edge. 



This highly polished bowl carved 
of obsidian was dug up at the 
site of the village of Tepe Gawra 
(see map). 




January 6, 1969 



SCI ENCE I ' lilffl l i l * 



Exploring Winter 
Ice 



by David Webster 



The ice that forms on a pond or lake 
keeps changing until it disappears. 
You can observe some of these changes 
and use a refrigerator to investigate 
how they take place. 




Is the lake now freezing over, or unfreezing? 



■ One of the strangest changes in nature is the freezing and 
thawing of a pond. In just a few days the blue water silently 
changes into a hard sheet of ice. In the spring, usually with 
equal suddenness, the water in the pond reappears. You 
can learn more about ice by watching a pond and by in- 
vestigating what happens as water freezes. 

The water in a pond reaches its warmest temperatures in 
late summer. The pond then begins to cool because of the 
colder autumn air. As water at the surface of a pond cools, 
it becomes more dense and sinks to the bottom of the 
pond. (See "How Dense Are You?", N&S, September 30, 
1968.) To get an idea of how this happens, float an ice 
cube in a glass of warm water. Drop a little ink or food 
coloring liquid on top of the ice and watch how the cold, 
colored water moves in the warmer water. 

From Water to Ice 

In a pond, warm water from the bottom is pushed up to 
the surface by the colder water as it sinks. This natural 
circulation of the water is known as pond turnover. Ani- 
mals that spend the winter sealed beneath the ice depend 
upon the air that is dissolved in the surface water that 
sinks to the bottom. 

Water, like other liquids, "shrinks" and becomes more 
dense as it is cooled. But when it reaches a temperature 
of 39° F., a strange thing happens. The water begins to 
expand, and become less dense, when cooled below this 
temperature. Since ice forms when water is cooled to 32°, 
ice is less dense than water, and floats in it. 

Look at an ice cube floating in a glass of water. How 
much of the ice is under water? Do you think that water 
is a lot denser than ice, or just a little bit? Salt water is 
more dense than fresh water. Does an ice cube float a 
lot higher in salt water than in fresh water? Make some 
salty water and find out. Can you find any liquids in 
which an ice cube will not float? Try milk, kerosene, 
alcohol, salad oil, and orange juice. 



Have you ever noticed how ice cubes frozen in a metal 
tray have a little bump on the top? The bump forms be- 




How might ice have helped to split this rock? 

cause the middle of an ice cube freezes last. So the extra 
volume of the expanding ice is pushed up in the center. The 
force exerted by freezing ice is tremendous. It can break 
car radiators, water pipes, rocks, and even the concrete 
walls of a swimming pool. 

Fill a bottle with water, cap it tightly, and put it outside 
on a cold night. Place the bottle inside a tall, empty 
fruit juice can or milk carton, because the expanding 
ice will probably break the bottle. Does it shatter into 
many little pieces, or just along one crack? Will a bottle 
of water break if it is left uncapped or if it is only partial- 
ly filled? What happens to an unopened can of fruit 
juice, a water balloon, or an open bucket of water when 
the liquid freezes? 

Study a Pond, Make a Lake 

If there is a pond or lake near where you live or go to 
school, watch it as the weather becomes colder. You will 

NATURE AND SCIENCE 



probably see that the ice forms first next to the shore. One 
reason is that when the sun goes down, the soil and rocks 
along the shore lose their heat to the cooler air even faster 
than the water loses its heat to the air. This makes the 
water lose heat to the soil and rocks faster than it loses 
heat to the air. 

Also, the water is shallow near the shore, so there is less 
water to cool there than at the middle of the pond. (Which 
cools faster, a bathtub full of water, or a glassful of water 
at the same temperature?) 

In the early stage of freezing, a pond becomes rimmed 
by a paper-thin layer of ice. This usually occurs at night, 
during the first "cold snap." Should a strong wind develop 
the next day, the fragile ice might be broken up by waves 
and blown to the shore. Otherwise, the pond will freeze 
over completely if the cold weather continues. Why doesn't 



If you get to a lake 
before it is complete- 
ly frozen over, you 
will see that the ice 
forms first along the 
shore. 




a bump form in the middle of the pond, as it does in an 
ice cube? 

You can watch ice formation by making miniature lakes. 
Cover the bottom of a jar with water, then put it in the 
freezer and peek at it every 15 minutes. Where does the 
ice form first? Which freezes last, the water in the mid- 
dle, or along the bottom? Why does the jar of water 
freeze in a different manner than a pond? 

Will a large amount of water freeze as fast as a smaller 
amount? Try it and see. Large lakes usually require much 
longer to freeze than small ones. In the same town, you 
should be able to find open stretches of water in large 
bodies of water long after the smaller lakes and ponds are 
completely frozen over. 

At what spots does the pond you are observing freeze 
last? One way to locate the deeper places in a pond or lake 
is to notice where the water freezes last. Ice formation is 
also slowed down by moving water; sometimes the water at 
a lake's inlet never freezes at all. As long as ducks continue 
swimming in the same place, the water around them will 
remain free from ice for a long time. 




Why hasn't the water frozen in this river channel? 







Are the birds gathered here because the water is unfrozen, 
or is the water unfrozen because the birds are gathered 
here? Or both? 

Clear Ice, "Black" Ice, White Ice 

The first ice that forms on a lake is usually clear. The 
ice may look black, though, because you can see through 
it to the dark water below. After a few weeks, clear ice on 
a lake usually turns into the more familiar white ice. How 
long does the clear ice remain on the lake you are watch- 
ing? The milky color of white ice comes from tiny air 
bubbles that get frozen into it. The surface of the ice can 
become wet when some of the ice melts during a warm day. 




What made the 
pattern in this 
block of ice? 



Then the meltwater turns into white ice when it is refrozen 
at night. Often snow that falls on the ice is later turned into 
slush by the sun and warm air. Also, decaying plants at the 
bottom of the lake give off gas bubbles that rise and become 
trapped under the ice. (Continued on the next page) 






January 6, 1969 



Exploring Winter Ice (continued) 

Look at an ice cube. What part of the ice contains most 
of the white air bubbles? As the water freezes from the 
outside, the air that it contains is forced into the middle. 
The air bubbles in the last water to freeze make the ice 
white. Can you make an ice cube that is completely 
clear? Probably not. (The clear ice served at restaurants 
is made in a can whose sides are cooled by a liquid at 
10° F. Compressed air pumped through the center of 
the can bottom bubbles up through the water and out at 
the top. This keeps the water circulating past the sides 
of the can, where it gradually freezes. The core of white 
ice is removed from the cylinder of ice before it is cut 
up into clear cubes.) 

The Ice Thickens 

Unless snow falls on the ice, it grows thicker only from 
the bottom. The air temperature may rise above freezing 
during the day, warming the ice, and perhaps even melting 
the top layer. But as the air temperature drops below freez- 



Can you guess why 
the ice looks black 
around the pilings? 




ing during the night — say to 10° — the ice will gradually 
cool to 10°, and more water will freeze along the bottom 
of the ice. 

You might think that if the air temperature stayed below 
freezing long enough, the lake would freeze solid. But as 
the ice gets thicker, it takes longer for the ice at the bottom 
to reach the same temperature as the air. In time, the ice 
gets thick enough so that the cold air is never able to cool 
the bottom surface of the ice below 32°, and no more ice 
can form. 

You can use a thermometer to measure the temperature 
of water as it becomes ice. Put a thermometer in a jar 
of water in your freezer. Record the temperature every 



15 minutes. What do you notice about the temperature 
of the water once the ice begins to form? Does the ice 
ever reach the same temperature as the air in the freezer? 

How thick does the ice get on lakes? Chop holes into the 
ice with an axe or hatchet. Is the ice thicker near the shore 
or in the middle? When you cut through the ice, how far 
does the water rise in the hole? (Be sure to check with your 
parents before walking out on any ice, though, and always 
have an adult with you. ) 

From Ice to Water 

As the weather begins to warm up in the spring, the ice 
on a pond starts to melt quite rapidly. Most of the melting 
takes place at the bottom of the ice. Even though the water 
under the ice is just a few degrees warmer than the freezing 
point, it melts the ice more than the warm air above does. 

Will an ice cube melt faster in cold water or in warm 
air? Get two ice cubes of the same size. Put one of 
them in a glass of cold water and the other one in an 
empty glass at room temperature. How long do you 
think it will take for each ice cube to melt? Watch and 
see. What would happen if the investigation were re- 
peated in the refrigerator? 

When the weather gets warm, the air bubbles in pond 
ice spread out in all directions, until the ice becomes com- 
pletely honeycombed. The ice disappears first where it 
froze first— along the shore. (Can you guess why?) Soon 
all of the ice left becomes so weak that it begins to break 
up. Once this happens, the ice disappears as suddenly as it 
came. Ice that was once solid enough for walking on can 
disappear completely in a week ■ 

Does a crushed ice cube melt faster than a whole ice 
cube? Get two glasses of water and two ice cubes of the 
same size. Crush one ice cube by wrapping it in a cloth 
and hitting it with a hammer. Put the cracked ice in one 
glass and the whole ice cube in the other. Does the 
broken-up ice melt much faster? Why do you think ice 
cubes are sometimes made with a hole through them? 

— ANSWERS TO QUESTIONS ON THE COVER — 

• A plant stem loses its heat to the cold air faster 
than water loses its heat to the air. This makes the 
water lose heat to the plant stem faster than it loses 
heat to the air, so the water freezes first around the 
stem. 

• The moving water melted the bottom layer of the 
ice on the stream. Then icicles grew down from the 
remaining ice, until they touched the stream. The 
stream water then refroze around the icicles. 

• After a puddle has frozen over, the water remain- 
ing beneath the ice often sinks into the ground. 

• A light snow fell on the lake ice. Then the snow 
melted around breaks in the ice where water could 
touch the snow. 



\ M'URE ANnSCik\< I 



auinbi 



mmrunur 



Tales 



Told 



ky Trails 



by Dave Mech 



Whether you live in the city or the country, you can 
study the lives of wild animals by following their tracks. 



■ The best way to learn an animal's ways is to watch the 
creature. But that often is impossible. Many animals are 
active only after dark, and those that are active during day- 
light are usually too wary to let you near. This shouldn't 
stop you, though. Simply look for clues that might reveal 
their habits. 

The most useful kind of clues are tracks. These show up 
best in mud, sand, dusty roads, and snow. You don't need 
to venture into the deep wilderness to find the tracks of 
wild animals. Within the limits of most big cities, you can 
discover tracks of such mammals as rabbits, squirrels, 
mice, opossums, raccoons, and skunks. 

Look at Your Own Tracks 

You already know at least one track— your own. First 
chance you get, take a look at your bare-foot print. How 
does it differ from the tracks of other animals? Right away 
you will notice that it is larger than almost any other track 
you will find. So you know that size can help you tell one 
kind of track from another. 

Now compare your track with the track of a dog. You'll 
find at least three more important differences: (1) Your 
track is long, whereas a dog's is round. (2) The toes are 
all at the front of your track, but a dog's toes are on the 




CSf —*+ 



ON THE TRAIL OF A WOOZLE 

Do you remember the story of how Winnie-the-Pooh 
and Piglet tracked the mysterious Woozle? As they 
walked around and around a clump of trees, they 
found more and more Woozle tracks ahead of them. 
What was the Woozle? 

(Drawing by E. H. Shepard from Ihe book Winnie-the-Pooh by A. A. Milne. Copyright. 1926, 
by E. P. Dutlon & Co., Inc. Renewal, 1954, by A. A. Milne. Reproduced by permission of the 
publishers. ) 



January 6, 1969 



front and side of the track. (3) A dog has only four toes.' 
Remember differences in shape, for they will help you tell 
the tracks of one animal from those of another. 

Before you can learn much more about tracks, you need 
some experience with different kinds. Winter is the best 
time to get this experience if you live in the northern states. 
(In areas without snow, you will have a harder time, but 
you can still study tracks in wet or dusty areas. ) A day or 
two after a snowfall, go looking for fresh trails. Be sure to 
arm yourself with a ruler or tape measure, a notebook, 
a pencil, and perhaps a camera. 

How To Study Tracks 

Fields, woods, vacant lots, and even your own backyard 
are good places to find tracks. Look around bushes, logs, 
trees, brush piles, and along fences or hedges. When you 
find a track, examine a single print. How long is it? How 
wide? How many toes does it have? Make a drawing of 
the print and jot down the measurements. 

Then measure and sketch the spacing of the tracks. Is 
each print spaced evenly in a trail? Or are there two, three, 



SINGLE PRINTS SPACED EVENLY 

m 









m 



9W3 



GROUPS OF PRINTS BUNCHED TOGETHER 



or four tracks bunched together? How far apart are the 
groups? If you have a camera, put your ruler near the 
tracks and take a picture of them. Jot down a note about 
where and when you photographed them. 

Make the same sketches, measurements, pictures, and 
notes for each different kind of track you find. Then you 
can compare them with the drawings on pages 8 and 9, or 
with tracks shown in books (see listing at the end of this 
article). You can best identify large tracks by looking at 
individual footprints. Smaller tracks can most easily be 
told by the pattern of their groupings. 

When you recognize most of the tracks in your area, 
your detective work has just begun— and so has the fun. 

(Continued on page 10) 









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Talcs Told by Trails (continued from page 7) 

The next step is to follow a set of tracks. That is the way 
you learn about how an animal lives — how it gets its food, 
what it eats, where it lives, how far it travels, and so on. 

One very important rule to keep in mind when tracking 
is never to step on the tracks. You may have to examine 
them again. I learned this from a cottontail rabbit I once 
followed. After I had tracked it for several minutes, the 
track suddenly ended. I had almost decided that the rabbit 
had sprouted wings when I thought of another answer. 
Perhaps it had turned around and gone backwards on its 
own track. 

Upon looking at the rabbit"s trail, I found it all scuffed 
out by mine. I couldn't tell whether or not it had back- 
tracked. But by watching carefully along both our trails, I 
found where the rabbit had taken a long leap off to one 
side. Then it had continued on its way. As I kept on the 
trail, the rabbit did the same thing six times. But I had 
learned, and was able to figure it out each time. 

After you track an animal a little way, you may notice 
that its pace changed. Try to figure out what the animal was 



A RABBIT'S HIND FEET LAND 
AHEAD OF ITS FRONT FEET 




doing. A good way to get clues about its pace is to study 
your own tracks again. First walk for several feet. Then 
hop. Then run at different speeds. Notice how different 
your tracks look each time. To imitate a rabbit or squirrel 
track, lean forward and put your hands into the snow. 
Then hop, using your hands for leverage and bringing your 
feet around in front of them. Remember how the track 
looks, for it will help you tell which way a rabbit or squirrel 
track is headed. Usually their hind footprints are ahead 
of their front footprints. 

When you are tracking an animal, take notes on how 
far it travels, what kind of living place, or habitat, it uses 
(fields, woods, swamps), and what it eats. If you can 
follow it a long way, draw a map of its travels. Try to 
figure out why it goes where it does. If you find its den, 
note whether it is a hole in the ground, a hollow log, a tree, 
or what. Keep notes on where it is so you can come back 
and track the animal again. 

This is exactly the method that scientists sometimes use 
to study the lives of animals. For instance, some biologists 
in Michigan followed over 2,000 miles of fox trails. They 
kept track of everything the foxes ate. Their findings sur- 
prised those people who thought that foxes eat mostly 
10 



game animals, such as pheasants and rabbits. In one study, 
the foxes were trailed for 577 miles and killed only three 
pheasants in that distance. In another area, they killed 
only five rabbits, two quail, and one hare in over 1,000 
miles. Both studies showed that the foxes' main food was 
mice, shrews, and carrion (dead animals). 

Solving a "Whodunnit" 

Probably the peak of your tracking career will come 
when you figure out a "Whodunnit"— a group of tracks 
where one animal chased, caught, and killed another. I 
saw such a set of tracks last spring (see photo). A fox had 
come upon a fresh muskrat track and followed it. Where 
the fox caught up to the muskrat there was blood and sign 
of a scuffle. Only one track left the area— the fox's. 

There is much more to learn about tracking. With expe- 
rience you will learn to tell an old track from a fresh one. 
You can learn to predict where certain animals will cross 
roads, streams, and valleys. But these things take experi- 
ence, and there's only one way to get that. Put on some 
warm clothes and go look for some tracks. And don't 
forget your notebook and pencil ■ 

Look in a book store or library for these books on animal 
tracks: The most complete book on tracks and other animal signs 
is A Field Guide to Animal Tracks, by Olaus Murie, Houghton 
Mifflin Co., Boston, 1954, $4.50; a mammal identification guide 
that includes track information is A Field Guide to the Mammals, 
by William H. Burt, Houghton Mifflin Co., Boston, 1952, $4.50; 
also look for Animal Tracks and Hunter Signs, by E. T. Seton, 
Doubleday & Co., Inc., New York, 1958, $3.95; Animal Tracks, 
by George F. Mason. William Morrow and Co., New York, 1943, 
$2.75; Field Guide to Animal Tracks, The Stackpole Co., Harris- 
burg, Pa., 1958, $1.50. 



*► 



The tracks on the left side 
of this photo are those of 
a fox, tunning parallel to 
the trail of a muskrat. Be- 
tween the muskrat's foot- 
prints is a mark left by the 
animal's dragging tail. The 
muskrat's trail ends in the 
maze of tracks at the top 
of the photo. (The large 
footprints crossing the 
photo were made by the 
author.) 




PHOTO 

How can sea 

gulls stand 

on water? 






prepared by 
DAVID WEBSTER 



ANSWERS TO BRAIN-BOOSTERS 
IN THE LAST ISSUE 



Mystery Photo: The icicle formed under the roof of the 
house, where the wire is attached. When the weather be- 
came warmer, the icicle broke away from the roof and 
slid down the wire. 



What would happen if? Block 3 would slide off the turn- 
table first, followed by block 1 . If block 2 were in the exact 
center of the turntable, it would never slide off. What 
would happen if marbles were used instead of blocks? 



Can you do it? It is impossible to "float" a needle on soapy 
water. Soap weakens the surface tension of water so that 
it will not support a needle (see " 'Surfing' to Safety," N&S, 
October 14, 1968). 



Fun with numbers and shapes: The diagram shows a way 
to draw the broken line without making any measurements. 



First draw two e 



s (A in diagram) at right angles to 
the ditch. Connect the ends of 
the lines with a long line (B) that 
goes past the corner of the house. 
Then draw two lines (C) that are 
at right angles to line B and are 
the same length as lines A. Draw 
a line (D) through the ends of 
lines C to mark the place where 
the rest of the ditch should be 
dug. 



For science experts only: The position of the fly in the 
train car will not change as the train stops. The fly is 
"cushioned" by the air in the car as the air gradually comes 
to a stop with the train. 







-e> 



WHAT WILL HAPPEN IF . . . 

. . . you freeze a jar of water that has an ice cube floating in 
it? Can you see the ice cube after all the water has turned 

intO ICC Submitted by Darlene Critchfield, Arlington, Virginia 



CAN YOU DO IT? 

Put 5 teaspoons of cornstarch into a cup. Into another cup, 
put 4 teaspoons of cornstarch and 1 teaspoon of baking 
soda. Now have someone shuffle the cups around so you 
don't know which is which. Can you make a test to tell which 
cup contains the baking soda? (You probably won't be able 
to taste any difference.) 



FUN WITH NUMBERS 
AND SHAPES 

Each of these three shapes 
measures the same length 
around the outside. Do all 
three shapes have the same 
amount of space inside them? 



FOR SCIENCE EXPERTS ONLY 

When I put my hand under cool running water from a 
faucet, the water feels cold. But when I drink the same 
water, it feels much warmer. How can this be? 

Submitted by Skip Williams, Pittsburgh, Pennsylvania 

JUST FOR FUN 

Pour a little vinegar into a jar and drop in a number of dif- 
ferent materials. Try a rock, a penny, a 
piece of chalk, a seashell, and some 
salt. The vinegar should be shallow 
enough not to cover up the materials 
completely. Look into the jar each day 
and see what changes occur. 



11 






rt auitiNi^t wisitni 



After hatching from eggs and digging up to the sur- 
face of the sand, young green turtles in some mys- 
terious way find the direction of the sea. 







In the last issue, the author told 
why the number of eggs laid by 
sea turtles is so important for 
the survival of these animals. 
Now Dr. Archie Carr tells what 
has been learned about how 
young turtles find their way to"* 
the sea, and where they go after 
disappearing in the surf.*^ 





HOW DO TURTLES 
FIND THE SEA? 



BY ARCHIE CARR 



■ Two mysteries about green sea turtles are how the 
newly-hatched turtles find the sea, and where they go after 
they enter the surf. The trip to the water begins when the 
turtles break out of the nest buried in sand on the beach. 
The nest may be in full view of the sea. More likely, how- 
ever, the nest is located so that the baby turtles, or hatch- 
lings, see nothing but sand and sky. 

The little turtles have to find the water, and unless they 
are eaten they nearly always do. They come out of the 



This article is adapted in part from the book, So Excellent a Fishe. 
/>.v Archie Carr, published by The Natural History Press, Garden 
City, N.Y. Copyright © 1967 by Archie Carr. 



12 



nest and, almost at once, begin to crawl in the general 
direction of the sea. They move around, through, or over 
obstacles. They go up or down hills, sure of whatever sign 
it is that marks the ocean for them. They can find the 
ocean by daylight or at night, in all weather except heavy 
rain, with the sun or moon hidden or shining brightly in 
any part of the sky. Their main guiding sign is still a 
mystery. 

Clues Along the Beach 

Although sea-finding seems to involve light, it is not a 
simple urge to move toward light. Otherwise the hatch- 
lings would go toward the sun or moon, which they only 
rarely do. Sometimes they do get led astray by an arti- 

s A TURF. AM) SCIENCE 



ficial light, or by some strong patch of natural light such as 
from a hole in the clouds. Most often, however, they move 
surely toward the water, no matter what the condition of 
the sky may be. 

After they leave the soft sand behind and reach the hard 
beach, there are other signs to guide them, such as the 
white foam of waves breaking on the beach. At night a 
lantern set beside the direct path to the water often draws 
a train of hatchlings toward it. By day a shiny or white 
object may do the same. 

The hardness and smoothness of the ground may cause 
the turtles to move faster for a moment. If a log blocks 
the way they move along it to the end, and then turn to 
the sea again. No normal feature of a beach keeps the 
turtles from following the main sea-finding signal, what- 
ever it may be. 

Several zoologists at the University of Florida, at 
Gainesville, set out to discover how the turtles find the 
sea. We learned that when hatchlings were blindfolded, 
they could not find the water. This seemed to prove that 
the turtles needed their eyes for finding the sea. In an- 
other test, we took some hatchlings just before they came 
out of a nest on an island in the Caribbean Sea. We flew 
them to the Pacific shore. There we allowed them to come 
out of an artificial nest back in the dunes. They went di- 
rectly to the strange ocean, even though it was completely 
hidden from their sight. 

More tests were needed to find out what turtles see on 
beaches, and what kinds of light they need to help them 
find the sea. Dr. David Ehrenfeld, now Assistant Professor 
of Zoology at Barnard College in New York, began a 
series of experiments in which he put eye glasses with 
changeable lenses on adult turtles (see photo). 



The lenses for the glasses were colored to let through 
light of one of the colors that make up white light. A lens 
that let in only green light seemed to make no difference 
at all in the ability of the turtles to find the water. Lenses 
that let in only blue light caused a little trouble, but those 
that let in only red light seemed to make it very hard for 
the turtles to find the water. It seems that there is some- 
thing about green and blue light that tells a turtle the 
direction of the sea. Or, maybe turtles just see better in 
green and blue light. 

By Land or by Sky? 

Later, Dr. Ehrenfeld wanted to find out whether turtles 
were using certain colors of light from the sky, or the 
outline of the land, to guide them to the sea. He made a 
round testing area 42 feet across, surrounded by a wall 1 8 
inches high. The wall and some palm trees planted in the 
area hid details of the surroundings from turtles inside 
the circle, without blocking the light from the sky. 

At different times of the day and night Dr. Ehrenfeld 
used a device called a spectrophotometer to measure the 
amounts of red, blue, and green light coming from the 
sky over the sea and land. Then he released hatchlings in 
the center of the testing area and watched to see the di- 
rections they chose. The spectrophotometer showed no 
differences between the light in the sky over the sea and 
that over the land. 

The turtles in the walled area had trouble finding the 
right way to the sea. Some of them headed inland. Many 
did not bother to move at all. Later the wall and trees 
were removed. When other young turtles were put into the 
testing area, most of them headed directly for the sea, even 
though it was not visible. (Continued on the next page) 






By putting special eyeglasses on 
sea turtles, Dr. David Ehrenfeld 
tried to discover if some color of 
light helps the turtles to find the 
direction of the sea. 



January 6, 1969 








Young green turtles are colored dark above and light below. 
This coloration may protect them from enemies as they 
drift and feed near the surface of the ocean. 



How Do Turtles Find the Sea? (continued) 

So it seems that whatever sign guides turtles to the sea, 
it is not located high in the sky, but low over the horizon. 
We still don't know for sure whether it is the color of light, 
or the outline of the land, or something else that guides 
them. Only further study may solve this mystery. 

Where Have All the Turtles Gone? 

Another puzzle is the disappearance of young sea turtles 
for their first year of life. At most of the known nesting 
grounds, the water in front of the beach is an unfit living 
place for the hatchlings. I haven't been able to find them 
there at any time after the hatching season. They must 
move farther out to sea. 

Other facts agree with that idea. The coloring of the 
young green turtle is like that of fish that live in the open 
ocean: dark above and white below (see photo). The 
white undcrparts make the turtle less visible to an enemy 
seeing it from below against the sky, while the dark back 
mixes with the dark depths of the water to hide the turtle 
from birds overhead. 

The most likely idea to account for the disappearance 
of the little turtles seems to be that they drift in the open 
sea for a time. If this is so, the turtles must be picked up 
by currents along the shore and carried wherever the 
currents go. The trouble with this idea is that nobody 
knows where the currents go. 

The search for the hatchling turtles goes on. The small- 
Dess and weakness of young turtles' jaws must keep them 

14 



in places where they can find plenty of small, soft-bodied 
animals for food. In tanks no more than two or three feet 
deep, they feed equally well at the bottom or at the surface. 
In deeper water, however, they have trouble finding and 
working with food on the bottom. Perhaps the young 
turtles live at the surface in some part of the sea where 
there is a sure supply of floating food. 

There is only one place I can think of where, at the 
surface of the open ocean, there might be food that baby 
turtles could find and eat. That place is in the North 
Atlantic in the Sargasso Sea (see map), which is filled with 
sargasso weed, a type of brown algae. It is estimated that 
10 million tons of sargasso weed float in that part of the 
ocean. Many animals live among the weeds and perhaps 
young sea turtles find their food among them. 

But I have never been able to find a place, or anybody 
who knew of a place, where young sea turtles could be 
caught. Wherever it is that hatchlings seem to lose them- 
selves, they cannot really be lost. They are just in some 
place that hasn't been thought of by zoologists. Until that 
place is found, there will be another big mystery in our 
understanding of the lives of sea turtles ■ 



UNITED STATES ^T 



SARGASSOS 



CUBA 



MEXIC 




The young turtles disappear after they enter the sea along 
the eastern coast of Central and South America. They move 
far out into the ocean, perhaps to the Sargasso Sea. 



NATURE AND SCIENCE 



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•###* 



This photograph was made by flashing a light on and 
off very rapidly while the pendulum made one swing, 
from right to left. 



■ If a 100-pound ball and a 1 -pound ball are dropped from 
the same height at the same time, will one hit the ground 
before the other? 

Some scholars of ancient times said that the heavier 
object would be pulled to the earth faster than the light 
object. There is no evidence that any of these scholars 
tried dropping weights to see what happens. Some said 
that objects fall too fast for the eye to follow them. Do you 
think this is so? Try it and see. 

Centuries later, in the 1 600s, the Italian scientist Galileo 
thought of another way to investigate falling objects. One 
story is that he got the idea as he watched a hanging lamp 
swing back and forth on its chain, after someone had 
pulled the lamp to one side to light the candles. 

As you might expect, the distance the lamp moved 
from one side to the other got shorter with each swing. 
But Galileo noticed that it took the same length of time 
for the lamp to swing from one side to the other, no matter 
how far it traveled during each swing. He also saw that 
during the downward part of each swing the lamp was 
falling, even though the chain kept it from dropping 
straight downward, as an unattached object falls. 

Galileo reasoned that if a heavy object falls faster than 
a light object, as the ancients said, then a heavy lamp 
should swing faster than one of lighter weight. You can 
test this idea, as Galileo did, by making a pendulum. 

Swinging Your Weight 

Tie or tape an object about as heavy as a golf ball to 
one end of a string about three feet long. Tie the other 

January 6, 1969 




end of the string to a wall hook or floor lamp so the weight 
can swing back and forth freely. Make the knot at the 
bottom of the hook and tie it tightly, so the string won't 
turn around the hook as the pendulum swings. 

Keep the string stretched straight 
as you lift the weight part-way up (see 
diagram). Then let go and watch until 
the pendulum stops swinging. You can 
see that each swing is shorter in dis- 
tance than the swing before it. Does a 
short swing seem to take any less time 
than a long swing? 

Use a watch with a second hand to 
measure how many seconds it takes your pendulum to 
make 10 full swings. (A full swing is from one side to the 
other and back again.) With this measurement, how can 
you figure out how many seconds it takes for just one full 
swing? 

Now attach a heavier weight to the string and time 10 
full swings. Also try a lighter weight. Do you think the 
weight of a pendulum makes it swing any faster or slower? 

What do you suppose Galileo decided about the falling 
speed of heavy objects and light objects? ■ 

-INVESTIGATION 

Before Galileo died he designed a way to use a pen- 
dulum to regulate a clock. The pendulum took one 
second for each full swing. Can you think of a way 
to change your pendulum so that it makes one full 
swing each second? Two full swings? Try it and see. 



15 



WHAT'S 
NEW 

by 

B. J. Menges 





20 million gray squirrels went on 
the move last fall, deserting their homes 
in North Carolina, Tennessee, Georgia, 
and Missouri. Apparently it all started 
the previous fall, when there were plenty 
of nuts and acorns for the squirrels to 
store for winter. As a result, more squir- 
rels than usual survived the cold weather. 
Last spring they produced a very large 
number of young. 

That same spring, frost struck nut- 
bearing trees, killing many flowers that 
would have developed into nuts and 
acorns. Last fall, when the squirrels 
started to gather nuts again, they discov- 
ered there would not be enough food to 
last through winter. Searching for food 
they could store, the squirrels moved 
farther and farther from their nesting 
areas, and many thousands of them died 
as they tried to cross highways, rivers, 
and lakes. 

Get out of town! This is the warn- 
ing some physicians are giving to resi- 
dents of Los Angeles, where smog has 
become a major health hazard. The smog 
forms when sunlight shines on smoke, 
gases, and other pollutants produced 
mainly by automobiles and industry (see 
"What's New?", N&S, September 16, 
1968). Cars alone pour over 12,000 tons 
of pollution into the air over Los Angeles 
each day. Once formed, smog often 
blankets the city for days at a time, 
trapped between sea breezes from the 
west and mountains to the east. The smog 
irritates the sensitive linings of people's 
noses, throats, and lungs, and also dam- 
ages plant life over a wide area. 

To reduce smog, Los Angeles forbids 
industry to use certain fuels, regulates 



the burning of rubbish, and requires that 
late-model cars be equipped with pollu- 
tion control devices. Even so, there is 
still about as much smog as there was 10 
years ago. If pollution controls had not 
kept up with the increasing amounts of 
pollution produced by the city's rising 
population, it might now be impossible to 
live in "The City of Angels." 

Painless injections are helping in 
the worldwide fight against smallpox, 
malaria, and other diseases that spread 
rapidly. The injections aren't given with 
hypodermic needles. Instead, vaccine is 
injected with a new type of spring- 
powered "gun." When the spring of the 
gun is compressed and then released, it 
shoots the vaccine through a tiny hole in 
the gun at a speed of 700 miles an hour. 
The stream of liquid pierces a person's 
skin so fast that he feels no pain at all. 

Since the injections are painless, peo- 
ple are less fearful of being inoculated. 
And because the device works quickly 
and economically, millions of people 
throughout the world can be protected at 
low cost. 

The world's tallest tree has been 
saved. This 385-foot redwood, recently 
discovered in California's Redwood 
Creek Valley, seemed destined for the 
lumberman's saw. But conservationists 
have now won a long, hard battle to cre- 
ate Redwood National Park in northern 
California. The second, third, fourth, and 
seventh tallest trees so far discovered are 
in the same forest. 

Lumber companies have already 
leveled many redwood forests. Only 
250,000 acres of unspoiled redwoods are 
left where there were once two million 
acres of the trees. Even though the new 
national park includes 32,500 acres of 
redwoods in its 58,000-acre area, many 
more trees should be saved. If the present 
rate of lumbering continues in the re- 
maining redwood forests, the trees that 
took many centuries to reach their ma- 
jestic heights will be gone within 20 
years. 

One of the strangest families in 

the animal kingdom has been discovered 
in Israel. This is the family of a species 
of hornet called Vespa oriental is. At the 
first stage in their development, these in- 
sects come out of their eggs as grubs, 
or soft, plump, wormlike larvae. They 
eat insects and other animal food brought 
to the nest by the adult hornets. As the 



grubs chew this food, saliva drips from 
their mouths. The adult hornets sip the 
saliva. 

The adults themselves cannot digest 
the foods they bring to the nest, accord- 
ing to Israeli scientists. But the saliva of 
the grubs changes these foods into a form 
that the adults can digest. Without the 
grubs, the adults would starve. This 
seems to be the only known case in the 
animal kingdom where the lives of the 
adults depend on the young. 

If skis always came off the instant 
a skier fell, there might be 20,000 fewer 
skiing injuries each year, according to 
Dr. Lawrence D. Sher, an Assistant Pro- 
fessor of Biomedical Engineering at the 
University of Pennsylvania, in Philadel- 
phia. Skis that remain fastened when a 
skier falls often get tangled and act as 
levers, pushing or twisting his legs. Many 
skiers fasten skis to their boots with a 
spring binding that is supposed to un- 
fasten when the pressure from the boot 
suddenly changes, as in a fall. But this 
doesn't always work, often because the 
skier has tightened the binding too much, 
in fear of losing his skis on a downhill 
run. 

Dr. Sher has enlisted a group of volun- 
teers to ski this winter with electronic 
devices on their boots that will measure 
the forces the boots exert on their bind- 
ings during skiing maneuvers. With that 
information, Dr. Sher believes, an "ideal" 
ski binding can be designed — one that 
simply fastens or unfastens, so it can't 
be overtightened, and always unfastens 
immediately in a fall. 



J>^ 




16 



NATURE AND SCIENCE 



Using This Issue . . . 

(continued from page 2T) 

Whether it proved anything is another 
question. 

Suggestions for Classroom Use 

After your pupils have offered their 
answers to the question beginning the 
article, have them drop two objects of 
different weight at the same time from 
the same height, and try to discover 
by sight or sound whether both land 
at the same instant. Try light and heavy 
books, a book and a pencil, a basket- 
ball and a golf ball, and a golf ball 
and a ping-pong ball, for example. 
Have them drop the objects while 
standing on the floor, standing on a 
chair or table, and standing at the top 
of a stairwell. 

Sometimes the objects may seem to 
land at the same time; other times they 
may not. Could some force other than 
the pull of the earth's gravity be affect- 
ing the fall of one object more than the 
fall of another? Your pupils will prob- 
ably suggest that a basketball is pushed 
upward more than a golf ball is by the 
air they fall through (see "Discovering 
an 'Ocean from the Bottom," N&S, 
Nov. 11,1 968). They can test this idea 
by dropping two sheets of paper, one 
flat, the other wadded into a ball. Both 
are the same weight, and the air pushes 
against each square inch of each ob- 
ject with equal force; but the flat sheet 
has more square inches of area for the 
air to push upward against. 

A golf ball and a ping-pong ball 
are nearly equal in area. So when they 
are falling at the same speed the air 
pushes upward on both with nearly 
equal force. But the golf ball's greater 
mass (the amount of material mak- 
ing it up) makes it resist the air's up- 
ward push more than the ping-pong 
ball resists it. 

By this point, your pupils will prob- 
ably be anxious to try Galileo's pen- 
dulum experiment, which can easily 
be done at home or in school. They 
will probably find, as Galileo did, that 
neither the weight of a pendulum nor 
the distance it swings changes its 
period — the period of time it takes to 
swing from one side to the other and 
back again. 

I January 6, 1969 



Topics for Class Discussion 

• Why does a pendulum fall in a 
curved path instead of straight down'.' 
The earth's gravity is pulling the un- 
attached end of the pendulum down- 
ward, and the hook is pulling the pen- 
dulum toward the hook. (Have your 
pupils try to draw a straight line from 
the top to the bottom of a sheet of 
paper while someone pulls the sheet 
sideways.) The pull of the hook 
doesn't slow the fall until the pendulum 
is directly below the hook. 

• Does a pendulum move at con- 
stant speed throughout its swing? It 
starts falling from a dead stop, moves 
fastest at the bottom of its swing, then 
slows gradually until it stops rising and 
begins to fall back down again. So your 
pupils can probably guess that it moves 
faster and faster as long as it is falling. 

• How does a pendulum complete 
a long swing in the same time it com- 
pletes a short swing? The longer the 
pendulum falls, the faster it is moving 
at mid-swing, and the farther it will go 
in the same time it took to make a 
shorter swing. 

• What makes an object fall? For 
convenience, we usually say it is the 
force of the earth's gravity pulling the 
object toward the earth's center of 
mass (see "Balancing Point," N&S, 
Nov. 13, 1967, page 2T). Actually, 
though, the earth and the object are 
attracted, or pulled, toward each other 
by a force called gravitational attrac- 
tion. This force exists between any 
two objects, and the closer they are, 
the stronger the attraction between 
them. (This is why an object moves 
faster and faster the longer it falls to- 
ward the earth.) 

The greater the mass of two objects, 
the stronger the gravitational attraction 
between them. It is stronger between 
the earth and a heavy object than be- 
tween the earth and a lighter object. 
However, the greater the mass of an 
object, the more resistance it offers to a 
force that tends to change its motion, 
and this resistance cancels the extra 
attraction between the earth and a 
heavy object. Dropped simultaneously 
from the same height, a light and a 
heavy object will accelerate at the 
same rate and will land at the same 



instant unless one is slowed up more 
than the other by air pressure. 

Brain-Boosters 

Mystery Photo. Sea gulls, of course, 
cannot stand on water. The birds in 
the photograph are standing on smooth 
ice. At the upper-right-hand corner of 
the photo, near the retaining wall, you 
can see where the ice has been broken. 

What will' happen if? After your 
pupils have tried to guess what will 
happen when you freeze a glass of 
water that has an ice cube in it, en- 
courage them to try it at home and see. 
The ice cube will still be visible in the 
glass of frozen water. 

Can you do it? Your pupils can ob- 
tain the materials necessary for this 
problem at home, or you can provide 
small amounts of cornstarch and a 
cornstarch-and-baking soda mixture in 
plastic bags. See how many pupils can 
make the correct identifications and 
explain to their classmates how they 
did it. 

The best way to find out which cup 
has the baking soda is to add some 
vinegar to both cups. Vinegar makes 
baking soda give off carbon dioxide, 
and you will be able to see the gas 
bubbling through the vinegar in the 
cup that contains baking soda. 

You might challenge your pupils to 
determine which of two cups of corn- 
starch contains other "mystery pow- 
ders," such as powdered milk, confec- 
tioner's sugar, plaster of Paris, salt, or 
flour. In many cases the presence of 
the mystery powder can be ascertained 
by taste, smell, color, or feel. (Caution 
the children against tasting any "mys- 
tery mixtures" of their own concoction 
without first asking an adult.) 

Fun with numbers and shapes. A 
circle always encloses a greater area 
than any other plane, or two-dimen- 
sional, geometric figure of the same 
length around (perimeter). Similarly, 
among solid, or three-dimensional fig- 
ures, a sphere encloses a greater vol- 
ume than any other figure of the same 
surface area. 

For science experts only. Different 
parts of the body vary in their sensi- 
tivity to heat. Water usually feels 
(Continued on page 4T) 

3T 



Using This Issue . . . 

(continued front page 3T) 

warmer to the mouth than to the hand. 

It is possible to change temporarily 
the heat sensitivity of parts of the body. 
An easy way to demonstrate this is to 
set up a pan of cold water and a pan 
of moderately hot water, with a pan of 
lukewarm water in between. Place one 
hand into the cold water and the other 
into the hot water, and keep them there 
for a minute or two. Then transfer both 
hands to the lukewarm water simul- 
taneously. The lukewarm water will 
feel relatively warm to the hand that 
has been in the cold water, and cool to 
the hand that has been in the hot water. 

Just for fun. Vinegar releases carbon 
dioxide from lime (calcium carbonate) 
just as it does from baking soda (so- 
dium bicarbonate). Chalk, a seashell, 
and a limestone rock all contain lime, 
so a bubbling reaction will be seen if 
they are placed in vinegar. Let your 
pupils drop other materials into the 
vinegar and see whether they can find 
another substance that probably con- 
tains lime. 



Books That Will Help You . . . 

(continued from page IT) 

of the wealth of material contained in 
this bulletin is found on page 8 — "Clue 
Words," a categorizing of 98 verbs de- 
scribing activity connected with science 
learning. 

Ideas for Science Investigations, by 

Victor M. Showalter and Irwin L. Sles- 
nick (1966, 58 pp., $2.25, Stock Num- 
ber 471-14500). Although this booklet 
was designed primarily for use by high 
school students, it can be of invaluable 
help to teachers, too. Part One presents 
suggestions for use of the book. Part Two 
shows how three high school students 
developed individual investigations into 
the same natural phenomenon, the rise 
of sap in plants. Part Three contains sug- 
gestions and sample questions for another 
kind of investigation. Part Four is a guide 
to references that can be of help in con- 
ducting any science investigation. The 
entries have been limited to those that 
are known to be of value. 

Investigating Science with Children 
Series (set of six volumes, 1964, $13.50, 
Stock Number 478-14280). Vol. 1, Liv- 
ing Things; Vol. 2, The Earth; Vol. 3, 



Atoms and Molecules; Vol. 4, Motion; 
Vol. 5, Energy in Waves; Vol. 6, Space. 
These handbooks have the distinguished 
sponsorship of two leading groups con- 
cerned with the improvement of science 
teaching: NSTA and NASA (the Na- 
tional Aeronautics and Space Adminis- 
tration). Each book in the series is con- 
cerned with a single area of science and 
moves from simple concepts to more 
complex ones within each chapter, so 
any teacher, at any grade level, should 
find that all of the books contain usable 
material. 

The question-discovery approach is 
used, and although the activities and 
learnings are purposely not graded, they 
are designated for difficulty by an x, y, 
or z. All six volumes are filled with help- 
ful illustrations, and each chapter con- 
cludes with a summary of the main ideas 
that have been developed. Throughout 
each book, cross-references are made to 
activities and science content found in 
the other books in the series. 

To ensure accuracy, leading scientists 
were asked to read and review the con- 
tent concerning their respective fields 
during the preparation of the manu- 
scripts. But there are no final answers 
in these books. Let the series be thought 
of as a challenge to further learning. 





to: nature and science 

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nature and science 

TEACHER'S EDITION 

VOL. 6 NO. 9 / JANUARY 20, 1969 / SECTION 1 OF TWO SECTIONS 

COPYRIGHT © 1969 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 




USING THIS ISSUE OF NATURE AND SCIENCE 
IN YOUR CLASSROOM 



£S? 



Life at the Top of the World 

This special-topic issue deals with 
a biome—a large area of land having a 
particular combination of climate and 
plant and animal life. The prairie and 
the tropical rain forest are examples of 
biomes. (The October 30, 1967 issue 
of N&S was devoted to the desert 
biome.) The tundra, subject of this 
issue, is the northernmost biome in the 

: world. 

. The word tundra comes from a Fin- 
nish word meaning "treeless plain." 
Tundra is dotted with lakes and bogs, 
and has low temperatures, a short 
growing season, and little precipita- 
tion. It is a land of low-growing plants, 

isuch as mosses, lichens, and rushes. 

\ A second kind of tundra, called al- 



pine tundra, can sometimes be found 
on high mountains where the climate 
is similar to that in the far north. But 
it is in the Arctic where the true tundra 
stretches for thousands of miles. Tech- 
nically, the whole Arctic region is not 
a biome, since it consists of both tun- 
dra and ocean. But parts of the Arctic 
Ocean might be considered an exten- 
sion of the tundra biome, since some 
tundra animals roam far out on the 
ocean ice in search of food. 

This Article briefly describes some 
of the characteristics of Arctic life. If 
time permits, you might discuss with 
your class some other features of the 
Arctic, including the "midnight sun" 
(see box), and an important group of 
(Continued on page 2T) 



JUNE 21 




DECEMBER 21 




You can demonstrate the "midnight sun" of the Arctic by moving a globe around a 
lighted bulb as shown in the diagram. (Keep the axis pointed in the same direction 
throughout.) With the globe at "June 21" position, rotate it once, showing that the 
jNorth Polar region is in daylight for 24 hours. At the "December 21" position, it is 
m darkness for 24 hours. 



>*SW 



^ 



nature - 
and science 

IN THIS ISSUE 






(For classroom use of articles pre- 
ceded by •, see pages 1T-4T.) 

• Life at the Top of the World 

An introduction to the Arctic, land 
of tundra, sea ice, and a 10-month 
winter. 

• Survival in the Arctic 

Through adaptations in their bodies 
and behavior, Arctic mammals live 
year round in the harsh northern 
environment. 

• Brain-Boosters 

• Snow, Sixty Below, and the 
Eskimo 

A Wall Chart shows how Eskimos 
use the limited resources of the Arc- 
tic to get food, stay warm, and build 
snug homes. 

• The Ups and Downs of Animal 
Numbers 

Certain animal populations seem to 
rise and fall in regular cycles. 
Whether this is so — and if so, why — 
is still a mystery. 

The Great Bear of the North 

How biologists use modern de- 
vices, including satellites, to learn 
more about the little-known polar 
bear. 

The Land That Keeps Its Cool 

Life in the Arctic is complicated by 
the deep-frozen soil and its thin 
active layer that thaws into mud for 
a few weeks of the year. 

IN THE NEXT ISSUE 

An astronomer tells of the trials and 
tribulations of lifting a telescope 
high in the atmosphere with a 
balloon ... A visit to Flatland — a 
two-dimensional world ... A Wall 
Chart shows how optical telescopes 
work . 



Using This Issue . . . 

(continued from page IT) 



plants common to the tundra, the 
lichens (/v-kens). One of the most 
abundant kinds of lichens is called 
reindeer moss (though it is not a moss). 
As the name implies, this lichen is an 
important food for reindeer and cari- 
bou. A lichen consists of two kinds of 
plants, algae and fungi. Both kinds 
benefit from living together: the fungi 
obtain food from the algae; the algae 
obtain protection and water from the 
fungi. Neither could exist alone. This 
"partnership" is called mutualism. 

Survival in the Arctic 

This article offers several examples 
of ways in which Arctic animals have 
become adapted through evolution to 
survive in the far north. An adaptation 
can be defined as any aspect of an 
organism that promotes its welfare, or 
the welfare of the species to which it 
belongs, in the organism's normal en- 
vironment. 

Adaptations can be lumped into 
these categories: 

1 ) Morphological adaptations in- 
clude the shape, size, structure, and 
color of an animal, and of its parts, 
such as feet, teeth, and beaks. The long 
fur of Arctic mammals is one ex- 
ample; the white fur of the Arctic fox 
and the white feathers of the snowy 
owl are others. 

2) Physiological adaptations refer 
to processes within the animal's body; 



NATURE AND SCIENCE is published for The American 
Museum of Natural History by The Natural History 
Press, a division of Doubleday & Company, Inc., fort- 
nightly September, October, December through March; 
monthly November, April, May, July (special issue). 
Second Class postage paid at Garden City, N.Y. and at 
additional office. Copyright © 1969 The American 
Museum of Natural History. All Rights Reserved. Printed 
in U.S.A. Editorial Office: The American Museum of 
Natural History, Central Park West at 79th Street, 
New York, N.Y. 10024. 



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calendar year (17 issues) $3.75, two years $6. Single 
copy 30 cents. In CANADA $1.25 per semester per 
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2T 



for example, the ways in which Arctic 
mammals are able to maintain differ- 
ent temperatures in two different parts 
of their bodies (see text of article). 

3) Behavioral adaptations include 
the undersnow burrowing of small 
Arctic mammals and the ability of the 
polar bear to find, stalk, and kill seals. 

It usually takes many generations 
for a species of animal to become 
adapted in such ways. However, an 
individual animal may have the ability 
to adjust to a change of environment 
during its lifetime (see "Getting Used 
to the Cold," page 6). This ability is 
called adaptability, and it is inherited, 
just like white feathers or thick fur. 
So adaptability is also an adaptation, 
which varies in degree from species to 
species. 
Topics for Class Discussion 

• Why is small size a disadvantage 
in cold climates? The diagrams on 
page 4 show how a large object is 
better able to keep heat than a smaller 
one. Arctic mammals tend to be larger 
than closely related mammals in 
warmer climates (though there are 
exceptions to this rule). 

• Why don't Arctic mammals 
avoid the winter cold by hibernating? 
When an animal hibernates, its body 
temperature drops to near freezing 
and all of its body processes slow 
down. In this way the animal sleeps 
for most of the winter, hidden in a den 
where the air temperature stays above 
freezing. If the temperature drops too 
low, however, the animal usually wak- 
ens. It then must find a warmer den, 
or it will die. Because of the Arctic 
permafrost, there are very few burrows 
where animals can find above-freezing 
temperatures, so the ability to hiber- 
nate has not evolved. 

• Of what advantage are small ears 
in the Arctic? There is a generaliza- 
tion, called Allen's rule, that states: 
Within any one species, protruding 
parts such as tails, ears, or bills tend 
to be shorter in colder climates than in 
warmer climates. Having relatively 
small extremities helps reduce heat 
loss in an animal (because less surface 
area is exposed to the air). 

This generalization is illustrated by 
the diagram of fox cars on page 6. 
Your pupils can find other examples 



of this phenomenon by looking at 
illustrations in mammal field guides. 
Have them look particularly at the tail 
length of rodents, such as mice, and 
the ear size of rabbits and hares. 

• Why must mammals and birds 
rid their bodies of excess heat? These 
two groups of animals are warm- 
blooded, maintaining a high, steady 
temperature by processes within their 
bodies. Your pupils may already know- 
that human body cells (especially 
those in the brain) can be damaged if 
the body temperature rises just a few 
degrees above normal. Most extra heat 
in humans is given off through the 
process of perspiration. Your pupils 
have probably seen dogs panting on a 
hot day; dogs "sweat" through their 
mouths. 

For Your Reading 

Animals of the North, by William 
O. Pruitt, Jr., Harper & Row, New I 
York, 1967, $5.95, is a collection of 
essays that reveals a great deal about 
the lives of such animals as wolves, 
hares, moose, and caribou. 

Snow, Sixty Below, Eskimo 

The Arctic has been the home of 
the Eskimo for 5,000 years. Today 
about 55,000 Eskimos survive. Their 
lives are rapidly changing as the Arctic 
becomes more "civilized." 

Arctic explorers and scientists have 
learned a great deal about survival by 
observing the cultural adaptations of 
the Eskimos. Long ago, the Eskimos ! 
discovered that two layers of light- i 
weight clothing are much warmer than 
one thick garment. Each layer of cloth- ! 
ing traps some air that is warmed by 
body heat and protects the person from 
cold. The inner layer of clothes (which 
arc usually made of animal skins) 
often has the furry part facing inside. 
The animal hairs also trap air. When 
an Eskimo is active, however, air cir- 
culates freely in the layers of light- 
weight clothes, carrying away excess 
heat. 

After your pupils have studied the 
Wall Chart, you might explain fur- 
ther the principle on which both the 
parka and the buildings of the Eskimos 
are based: warm air rises and cold air 
sinks. (Continued on page 3T) 



NATURE AM> St IENCB 



J 




>»* 




' «. 



~-.2Cr 



VOL. 6 NO. 9 / JANUARY 20, 1969 



iatujre 

nd science 






> — 



SPECIAL-TOPIC ISSUE 
IN THE ARCTIC 







■K_ 



nature and science 

VOL. 6 NO. 9 / JANUARY 20, 1969 

CONTENTS 

2 Life at the Top of the World, 

by Laurence Pringle 
4 Survival in the Arctic, by Penny Parnell 

7 Brain-Boosters, by David Webster 

8 Snow, Sixty Below, and the Eskimo, 

by Susan J. Wernert 
10 The Ups and Downs of Animal Numbers, 

by Dave Mech 
12 The Great Bear of the North, 

by G. Howard Gillelan 
15 The Land That Keeps Its Cool, 

by Margaret E. Bailey 



PICTURE CREDITS: Cover, p. 12, courtesy of National Film Board of Can- 
ada; pp. 2, 4, 6-11, 13, 15, drawings by Graphic Arts Department, The American 
Museum of Natural History; pp. 2-3, photo by Charles J. Ott, from National 
Audubon Society; p. 5, by Penny Parnell; p. 6, photo by Florence Weber; p. 
7, photo by Jonathan R. Gallant; pp. 8-9, photos from AMNH, except dog team 
by Bob and Ira Spring; p. 11, photo by Leonard L. Rue III; p. 13, photos by 
Dr. Martin W. Schein; p. 14, top by Richard Harnois, others by Dr. Martin 
Schein; p. 16, AMNH. 



PUBLISHED FOR 

THE AMERICAN MUSEUM OF NATURAL HISTORY 

BY THE NATURAL HISTORY PRESS 

A DIVISION OF DOUBLEDAY & COMPANY, INC. 

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" 




Ice . . . caribou ... 1 mo 
mosquitoes . . . snow . . 
These are all part of . . . 





The Arctic is made up of treeless land called tundra (she 
in green) and ice (shown in white). The deep-frozen grow 
called permafrost lies north of the dashed line. 



NATURE AND SCIENCE 









rif^W^' 






F winter . . . polar bears . . . 
s . . . Eskimos. 





_ 



ii ■ -**■ u*m 



Life at the top 
of the world 



■ Take an imaginary airplane trip to the North Pole. As 
the plane streaks north over Canada, you notice fewer cit- 
ies, towns, and highways. Lakes and evergreen forests 
stretch as far as you can see. Then the trees begin to thin 
out. They seem small and stunted, and grow in scattered 
clumps. Soon there are no more trees. Now you are over 
tundra — a land of bogs and ponds and nearly level ground 
covered with low plants such as mosses and lichens. 

North of the tundra lies the Arctic Ocean. And in the 
ocean, at an unmarked point somewhere below the drifting 
ice, is the North Pole (see map). 

From there, the Arctic stretches south in all directions. 
It ends at the southern edge of the tundra, called the tree 
line (although scientists don't always agree on the exact 
boundaries). Trees can't survive in the tundra because of 
the short growing season and because the Arctic is really 
a sort of desert. Not much snow or rain falls there, and 
most of the year the moisture is frozen so that plants can't 
use it. 

Opposite Ends of the Earth 

Whether you live in Florida or Minnesota, the weather 
is affected by cold winds from the distant Arctic. Winds 
from the Antarctic affect the southern half of the world in 
the same way. 

Antarctica and the Arctic differ in some important ways. 
The Arctic is made up of tundra and ocean. The ocean 
waters store heat in the summer and this helps lessen the 
cold of winter. The Antarctic, however, is a continent. It is 
much colder than the Arctic and is covered with about 
eight times as much ice. 

January 20, 1969 




Most of the year, the Arctic seems barren and lifeless. 
Then for about eight weeks in the summer the temperatures 
rise above freezing and the days become quite warm. The 
arrival of summer triggers great changes in the Arctic plant 
and animal life. In those few weeks of warmth, plants 
flower and produce seeds; insects hatch from eggs, develop 
into adults, and then lay eggs for next summer's generation; 
birds arrive from the south, build nests, and raise young 
that will fly back south with their parents before winter 
cold arrives. 

Only a few kinds of Arctic animals remain active all 
year long (see pages 4 and 12). Scientists like to study the 
plant and animal communities of the Arctic because life 
there is simple compared with that in warmer parts of the 
world. This simplicity of life may help cause the mysterious 
changes in the populations of many Arctic animals (see 
page 10). 

Eskimos have managed to live in the Arctic for thou- 
sands of years (see page 8). In the future, man will turn to 
the Arctic more and more, trying to find new sources of 
fuels, minerals, and food for the rapidly growing numbers 
of humans on earth. If man is to live comfortably in this 
land of bitter cold and deep-frozen ground (see page 15), 
he can learn a great deal from the Eskimos and other living 
things for whom the Arctic is home. — Laurence Pringle 



I Look in your library or bookstore for these books about the 
Arctic and its life: The Poles, by Willy Ley, LIFE Nature Library. 
Time Inc., New York, 1962, $3.95; Land of the Hibernating Rivers, 
by T. A. Cheney, Harcourt, Brace & World, Inc., New York, 1968, 
$2.95; Explorers of the Arctic and Antarctic, by Edward Dolan, 
Crowell Collier, New York, 1968, $3.95. 



U- 



SURVIVAL 

IN THE 

ARCTIC 

Some animals live year round in the Arctic. 

Scientists have discovered some of the 

ways in which animals such as sled 

dogs and caribou survive in 

this cold, barren world. 

by Penny Parnell 



■ Going barefoot in the snow is something that would not 
appeal to many people. But mammals living in the Arctic 
run on their bare paws over ice and snow at temperatures 
of 50 degrees below zero, Fahrenheit. 

Scientists at the University of Alaska's Institute of Arctic 
Biology, in Fairbanks, are studying how mammals are able 
to survive in the frigid temperatures of an Arctic winter. 
"Life in the Arctic proceeds at the same pace as in other 
parts of the world," says Dr. Laurence Irving, a Professor 
of Zoology at the Institute. "The animals here have the 
same needs as animals in other climates." 

Most Arctic mammals remain active all year long. Only 
a few go into the deep sleep called hibernation. Because 
mammals are warm-blooded (they have a high, steady 
body temperature), they must actively seek food each day. 
Most of their food is used to produce body heat. 

Somehow, the Arctic mammals survive. Over millions of 
years, they have slowly changed (evolved) in ways that help 
keep them alive and well through the long Arctic winters. 
Dr. Irving has been studying Arctic mammals for over 20 
years. To find out how the mammals can survive in such 
a cold climate, he has spent months living on the Arctic 
coast and traveling overland by dogsled. 

Sometimes it is so cold that batteries used in the scien- 
tists' equipment freeze unless they are carried inside the 
men's clothes. However, the scientists are able to measure 
the temperatures of many wild mammals, as well as the 
temperatures of the sled dogs they use. 

Asleep in the Snow at 30 Below 

The scientists have found that the thick fur of the land 
mammals keeps their bodies from losing much heat to the 

4 



air. (Sea mammals, such as seals, have thick layers of fat 
that help keep heat in their bodies.) Most Arctic mammals 
have an inside body temperature of 99 °F. The skin temper- 
ature of sled dogs resting in the snow was 91°, while just 
a few inches away from their skin, the snow in contact with 
the fur might be 60 or perhaps even 100 degrees colder. 

"We noticed that the sled dogs would curl up in the snow 
to sleep at 30 degrees below zero," said Dr. Irving. "The 



As a block gets bigger, its bulk 
(volume) increases faster than 
its surface area. In the same way, 
as an animal gets bigger, its 
heat-producing bulk increases 
faster than the surface area of 
its skin. Since an animal loses 
body heat through its skin, a big 
mammal is better able to keep 
body heat than a small one. 



VOLUME: 



8 blocks 
(increased 8 times) 




VOLUME = 1 block 

SURFACE AREA = 6 block-sides 



fes 



SURFACE AREA = 24 block-sides 
(increased 4 




NATURE AND SCIENCE 



wind would cover them with blowing snow, yet it did not 
melt on their fur. When they got up, the hollow place where 
they had lain would not be melted." 

The small Arctic mammals, such as mice, lemmings, and 
shrews, have a special problem. Because of their small size 
they lose heat more rapidly than bigger animals (see dia- 
gram). The small mammals could not carry enough fur to 
protect them from the cold. Instead, they spend most of the 
winter underneath the snow, digging tunnels in search of 
food and staying in nests made of grasses and moss. The 
temperature may be 15° in the nest while it is -40° or 
-50° at the surface of the snow. 

Turned on by the Cold 

Changes within their bodies also help to keep Arctic 
mammals warm. A drop in the air temperature may cause 
a change in an animal's metabolism— the chemical pro- 



SNUG IN THE SNOW? 

Is it as cold underneath of the snow as it is on top ? 
To find out, get two thermometers. Check to see that 
both shpw the same temperature. Leave one on the 
surface of the snow. Then, with your hand, make a 
small tunnel in the snow (at least a foot deep) so that 
you can put the other thermometer close to the 
ground. Fill in the hole you made, marking it with a 
stick so that you can get the thermometer out later. 
After 10 minutes or so, compare the temperatures of 
the two thermometers. Does snow seem to keep cold 
air from reaching the ground? See if it is warmer 
under snow that is even deeper. 



cesses within the body. Metabolism includes the "burning" 
of food and fat that produces heat. Warm-blooded animals 
have a certain level of metabolism (called basal metabo- 
lism) which keeps the body temperature normal while the 
animal is at rest. 

If there is a sudden drop in the temperature of the air 
around an animal, its body adjusts by speeding up the 
metabolic processes. Food is burned faster to produce extra 
heat. The air temperature that starts this speed-up is called 
the critical temperature. 

The critical temperature for some Arctic mammals is 
amazingly low. Scientists have found that the winter crit- 
ical temperature for the Arctic fox (see photo) is about 40 
degrees below zero. This means that the fox's metabolism 
doesn't usually speed up until the air temperature drops 
lower than -40°. In contrast, the critical temperature for 
most humans is about 80 degrees above zero. 

Arctic mammals (and some birds) are able to save heat 
by having two body temperatures — one for the main body 

January 20, 1969 




Mr. Gordon Hooten of the Institute of Arctic Biology pre- 
pares to take the body temperature of an Arctic fox. By 
studying mammals such as foxes, scientists at the Institute 
are learning how mammals survive the Arctic cold. 

and a much lower temperature for the legs and feet. Dr. 
Irving measured the skin temperature at different places on 
the body of a resting sled dog. While the air temperature 
was 22°F., the temperature of the skin on the dog's toe was 
46° and on its heel 32°. The skin temperature under the 
thick fur of the dog's flank, however, was 92°. 

An Arctic animal can keep cool temperatures on its legs 
and feet without lowering the temperature of its heart, kid- 
neys, and other vital organs. Inside the body, the arteries 
carrying warm blood toward the legs are close to the veins 
carrying cold blood back to the heart. The warm blood 
moving toward the legs loses heat to the cold blood rising 
from the legs. This helps keep heat in the animal's body. 

Too Much Heat in the Arctic? 

Strange as it may seem, overheating can be a serious 

(Continued on the next page) 



Survival in the Arctic (continued) 

problem in the Arctic. "If a man wears enough clothing to 
be comfortable while resting at 40 below, he will quickly 
become overheated if he starts running behind his dog 
team." explained Dr. Irving. "He has to be able to unzip 







When warm-blooded animals exercise, their bodies produce 
a great deal of heat. The extra heat must be given off so 
that the animals' body temperature can stay normal. These 
racing sled dogs lose heat from their open, panting mouths. 








Animals lose heat more easily 
from their legs, feet, and ears 
than they do from their bodies. 
The kit fox (1) has large ears 
which help it give off heat in its 
hot desert home. The red fox 
(2), which lives in colder areas, 
has smaller ears. The tiny ears 
of the Arctic fox (3) lose little 
heat to the air. 



his jacket, or to remove layers of clothing, to avoid over- 
heating. If he perspires so much that his clothes get wet, 
they lose their protective value. He may actually freeze to 
death because of overheating! 

"Dogs and caribou can't take off layers of clothing,''' Dr. 
Irving continued, "but we have noticed that they seldom 
become overheated." One reason that Arctic mammals 
seldom get too hot is that their fur lets cool air reach the 
skin when the animal is moving. They also lose heat wher- 
ever the fur is thin — on their stomachs, ears, and legs. 
They have long, moist tongues that hang from their mouths 
when they run (see photo). A lot of excess heat is lost from 
their open, panting mouths. 

Many questions are still unanswered in these studies of 
animals living in the frozen Arctic. Someday we may be 
able to understand all of the ways in which animals such as 
the little Arctic fox survive on the lonely ice floes of the 
Arctic Ocean. As the fox races across the sparkling ice, its 
body is perfectly adapted to the frigid climate. From mam- 
mals such as the Arctic fox, man may learn how to live 
more comfortably in the cold corners of the earth ■ 



GETTING USED TO THE COLD 



Polar bears and other cold-climate animals are able 
to live comfortably in the Arctic because they have be- 
come adapted to the cold over many generations. Men 
and other animals can adjust to a cold climate in a 
small way, or acclimatize, in a few weeks or months. 

Scientists at the Institute of Arctic Biology discovered 
that wild brown rats, raised in cold temperatures in a 
laboratory, could produce heat faster and faster as the 
temperature of the air dropped to —40°. Below that 
temperature, they could no longer keep warm. Then the 
same sort of test was given to a group of white rats 



that were not used to the cold. The temperature had 
only dropped to 10° when their bodies failed to pro- 
duce enough heat to keep them warm. 

Humans can also become acclimatized to the cold. 
When the weather warms in the spring, people who are 
used to the winter's cold may feel comfortable at 30° or 
40°F., and don't need to wear mittens, hats, or scarves. 
In the fall, however, when their bodies are not yet used 
to the cold, the same temperatures will numb their fin- 
gers and ears. Then they feel warm only when protected 
by extra clothing. 



\ ill HI A\n S( II \( I 




MYSTERY PHOTO 

The glass of water appears 
milky at the top because 
of air bubbles. How did 
the bubbles get into the 
water? 

Submitted by Jon Gallant, 
Bronxville, New York 



WHAT WILL HAPPEN IF . . . 

. . . you put a fish into a jar of water, then cover the jar and 
turn it upside down? Will 
the fish swim upside down 



for a while? 






">' 




Can you break a 

round toothpick 

held between 

three fingers as 

shown, without 

using your other 

hand? 




JUST FOR FUN 

Play a game of pendulum 
bowling. Hang a weight from 
a string so it just clears the 
floor. Set up some small 
matchboxes or dominoes on 
the floor near the pendulum. 
See how many ways you can 
find to arrange the match- 
boxes or swing the pendulum 
so that all the boxes get 
knocked over. If you don't 
change the way the pen- 
dulum is swinging, can 
it ever knock down a 
matchbox that it misses 
on the first full swing? 



A girl was born in the summer, but now her birthday is in 
the winter. How could this happen? 



FUN WITH 
NUMBERS 
AND 
SHAPES 

Which path 
is the one 
that would 
be made by a B 
pebble stuck 
in the tread 
of a bicycle 
tire? 








Mystery Photo: Sea gulls cannot stand on water. The birds in 
the photograph are standing on smooth ice. 

What will happen if? When the water is completely frozen, 
it is still possible to see the ice cube. 

Can you do it? The best way to find out which cup has the 
baking soda is to add some vinegar to both cups. Vinegar 
makes baking soda give off carbon dioxide gas, which will 
form bubbles. 

Fun with numbers and shapes: The circle has more space 
inside it than the square or triangle that are the same length 
around. Does a pound of clay fill the least space when it is 
shaped into a cube, a pancake, or a ball? 

For science experts only: Not all parts of the body are sen- 
sitive to hot and cold in the same way. Water of the same 
temperature can feel cool to your hand and warm inside 
your mouth. 



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In northern lands, the 

populations of many 

animals change greatly 

in the span of just a 

few years. Scientists 

are trying to solve 

the puzzle of . . . 




s ^ ) TV VV 



'/?&<$ 



■m— 

3 



I860 



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1880 



by Dave Mech 



1830 

TIME IN YFJ 






■ Scientists, like everyone else, enjoy good mysteries. Sci- 
entists called ecologists, who study the ways that living 
things fit into their surroundings, have long been interested 
in the mystery of population cycles. 

In most animal populations, numbers stay about the 
same from one year to the next. The story is different, how- 
ever, in the northern United States and Canada, especially 
in the Arctic region. There, the numbers of certain animals 
do change greatly from year to year. First, numbers go up 
for a few years, then they suddenly go way down. Then 
they begin to build again. Because these changes keep 
repeating, they are called cycles. 

Population cycles in North America come in two main 
lengths, one of about four years, the other of about 10. 
The 10-year cycle can be seen best in the yearly numbers 
of the Canada lynx (see photo ), a wildcat weighing about 
25 pounds. 

Ecologists first noticed lynx cycles when they looked at 
the records of the numbers of animal pelts taken by trap- 
pers. Arctic trappers usually sell their furs to the Hudson's 
Bay Company, which has kept records for more than 100 
years. During that time, the lynx catch has tended to go 
up and then down about every 10 years (see graph). When 
the catches were highest, trappers brought in up to 80,000 
pelts. When they were lowest, only a few thousand of the 
animals were trapped. 

Other animals whose populations seem to have 10-year 
cycles are snowshoe hares, ruffed grouse, red foxes, musk- 
rats, mink, and fishers (fox-sized mammals related to 



10 



weasels and mink). It also appears that other species ara 
cyclic in certain parts of the Arctic or at certain timesi 
In fact, some scientists believe they have found population 
cycles in everything from chinch bugs to tent caterpillarsj 
The four-year cycles are most easily seen in the nunw 
bers of Arctic lemmings— mouse-like mammals that live irj 
the far north. According to some people, these animals 
rush to the sea every three or four years and kill them-i 
selves. The story does have a bit of truth to it, for lemming 
numbers do get very large about every three or four years; 
and masses of the animals seem to go "mad" and move 
long distances. At times, some of them even drown in 
the sea. 

What Causes Cycles? 

Few scientists have the same views on Arctic popula- 
tion cycles. Some don't even believe there are cycles — 
they think there is something wrong with the figures. Most 
ecologists agree that the cycles exist. That, however, ii 
about all they agree on. 

Some think a three-to-four-year cycle is the basic one 
According to their idea, every third high point in the cyclt 
is the highest. This shows up as the peak of a 10-yeai 
cycle. These ecologists think that all the Arctic cycles an 
related. A few suggest that some unknown "outside' 
force causes the cycles. Such things as spots on the sun 
moonlight, and amounts of a certain gas in the air havf 
all been blamed for highs and lows of animal populations 

Some scientists claim that cycles come about just b) 

NATURE AND SCIENCE 




of Animal 
\ Numbers 



This graph shows the number of 
lynx skins bought from trappers by 
a fur company from 1860 to 1930. 
Notice how the numbers reach a 
peak about every 10 years. These 
ups and downs seem to be related 
to changes in the numbers of snow- 
shoe hares, which the lynx depend 
upon for food. No one knows why 
the hare numbers go up and down. 





1900 



1910 



1920 



1930 




nance. That is, in any string of numbers picked by chance 
by throwing dice, for example), the same number will 
ome up every so often. These scientists believe that 
;iance explains why animal populations reach a peak 
}/ery so often. By chance, they think, factors favoring 
igh animal populations might show up about every eight 
i 1 1 years. With smaller mammals like lemmings, they 
>ight occur sooner, causing three-to-four-year cycles. 
I Most ecologists believe there is a cause — or causes — 
]>r the population cycles other than chance. For example: 
ziould cycles in the numbers of predators, such as lynx, be 
msed by cycles in the populations of the animals that 
!e predators eat? This idea has possibilities. Communi- 
:s of plants and animals in the Arctic are simple com- 

ired to those of most of the world. Arctic animals tend to 

i 

impend on only one or a few other animals or plants for 
d. Thus a change in the numbers of one plant or ani- 
may cause great changes in the numbers of another. 
pr example, lynx depend on snowshoe hares for food, 
ihen the numbers of snowshoe hares drop, the numbers 
illynx also drop. But this fact still doesn't explain why 
owshoe hare numbers have ups and downs. 
A few ecologists believe that cycles of snowshoe hares 
ipend on the animals' food supply, the plants. Accord- 
y, to this idea, when hare numbers are low, few plants 
b eaten, so vegetation grows thickly. Then as hares in- 
case, their numbers reach a point at which they destroy 
list of the plants. Many of the hares starve. This gives 
plants a chance to grow again, and the cycle starts 

uary 20, 1969 



al 



over. The trouble with this notion is that it doesn't fit the 
facts — scientists seldom find large numbers of plants de- 
stroyed, no matter how many hares there are. 

When Stress Builds Up 

Another theory is based on something called stress. 
When animals are crowded together in cages, they suffer 
from stress, a kind of "nervousness" that makes them 
less healthy. The same is probably true in the wild. As 
animal numbers in the wild get larger, there is more and 
more stress. When numbers build too high, the animals 
have to hunt far and wide for food, and begin to fight. Then 
a sudden cold snap or blizzard may cause most of them 
to die suddenly. 

It is true that when snowshoe hare numbers "crash" 
(drop suddenly), scientists find animals dying from shock, 
the result of great stress. Also, Dr. Kai Curry-Lindahl, an 
expert on lemmings, believes that stress could account for 
the strange actions he has noticed in lemmings at the high 
point of their four-year cycle. But other scientists say that 
the stress theory doesn't explain why populations crash 
about the same time all over the Arctic. 

Scientists have worked on this mystery for over 30 years 
without coming up with a definite answer. Instead they 
are still asking questions. Do population cycles really ex- 
ist? If so, are they related to one another? Are they caused 
by some "outside" force, or do they result from an "inside" 
force like stress? Population cycles are still a fascinating 
science mystery ■ 



11 






Using "dart" guns, 
airplanes, and earth 
satellites, scientists 
are at last beginning 
to study the life of ... 



The Great Bear of the Nortt 



* 



m 



by G. Howard Gillela 



" 



i 







■ Biologists have learned a great deal about the lives of 
many wild creatures, but have only recently begun to study 
the polar bear. This great white ghost roams more than 
five million square miles surrounding the North Pole. The 
cold temperatures and dangers on the drifting ice make it 
difficult for men to study the polar bear. 

Another problem for scientists is that polar bears seldom 
come to land. They spend most of their lives on the ice 
of the Arctic Ocean, north of the territories of the United 
States, Canada, Denmark, Norway, and the Soviet Union 
(see map on page 2). Recently, biologists from these five 
countries have held meetings to plan studies of polar bears. 

One of the goals of the biologists is simply to find out 
how many polar bears there are. Estimates of the world's 
polar bear population run from 5,000 to 20,000. No one 
knows the total for sure, and no one knows whether polar 
bears are increasing or decreasing in numbers. Some biolo- 
gists believe that the bears may be in danger of dying out 
(becoming extinct). 

Scientists do know that polar bears feed almost entirely 
on seals. Sometimes a bear travels hundreds of miles in 
search of food. One mystery is whether a bear roams at 
random or travels in a particular direction. There is even 
some question about whether a bear could keep moving 
in the same direction if it wanted to. A polar bear's vision 
is apparently not strong enough so that the animal could 
guide itself by the stars. Also, there are few landmarks, 
such as hills or rivers, on the tundra and ice. The ice 

12 



itself drifts about three miles a day. If a polar bear can 
find its way under these conditions, its "guidance system" 
is worth learning about! 

"Shooting" Bears for Science 

One of the most important tools used by biologists in 
their studies of polar bears is a "dart" gun (see photo and 
diagram on next page). Instead of a bullet, this weapon 
shoots a hypodermic syringe (a device for pushing liquids 
into an animal's body). When the syringe strikes a bear, 
usually in the shoulder or hip, a drug is injected into the 
animal. The drug takes effect almost immediately, and the 
animal loses control of its muscles. It can still hear, see, 
and smell, however. 

The bear stays this way for about a half hour or less. 
But a scientist working quickly has time to measure the 
bear, clip a numbered tag to one of its ears, and take a 
blood sample. Sometimes the biologist uses a tattooing 
needle to mark permanent numbers on the inside of the 
bear's upper lip. He may also mark the bear with a large 
splotch of long-lasting, brightly-colored dye (see photo, 
right), so the animal can be easily seen from a plane. 

The biologists keep notes on each bear they mark. They 
record the date and location of the capture, the bear's 
sex and measurements, the numbers of the animal's tag 
and tattoo. If a bear is recaptured by scientists or shot by 
hunters months or even years later, the animal can be 
identified from the records. Then something may be 

NATURE AND SCIENCE 



EXPLOSIVE CHEMICAL 




After the syringe is loaded with a drug (above, right), it is put 
into a special gun (above) and shot at a bear. When the sy- 
ringe strikes the bear, a firing |$n is driven forward and 



causes a chemical to explode, forcing the drug into the ani- 
mal. The brightly-colored tailpiece on the syringe enables 
scientists to see where it strikes the bear. 



learned about the animal's growth and travels. 

To get within shooting range of a polar bear, the biolo- 
gists often use two airplanes that have skis for landing 
gear. When a bear is sighted from the sky, one plane lands 
at a point about two miles ahead of the bear. The pilot 
and one of the scientists then lie in wait behind a ridge 
of ice while the second plane "herds" the bear toward 
them. Since the range of the dart gun is limited, the scientist 
cannot shoot until the bear is dangerously close. The pilot 
stands by with a hunting rifle in case something goes 
wrong. 

Search for the Perfect Drug 

One of the pioneers in polar bear research is Dr. Vagn 
Flyger of the Natural Resources Institute at the University 
of Maryland, in College Park. Working with Dr. Flyger 



were Dr. Martin Schein of West Virginia University, in 
Morgantown, and Dr. Albert Erickson of the University 
of Minnesota, in Minneapolis. James Brooks of the United 
States Fish and Wildlife Service and Jack Lentfer of the 
Alaska Game Department are continuing to study polar 
bears in Alaska. 

Several years ago, Dr. Flyger used dart guns while 
studying deer. When the "weapon" was being considered 
as an aid in polar bear studies, he became interested in 
this new challenge. 

Dr. Flyger and the other biologists had some problems 
when they first began using the dart gun in the Arctic. In 
warmer climates, the gun worked well for distances up to 
70 yards. In the Arctic, however, the cold temperatures 
affected the gun so that it had a range of only 40 yards. 

(Continued on the next page) 




January 20, 1969 



When the drug takes effect, 
the polar bear cannot move 
for about 30 minutes. This 
photo shows Dr. Vagn Flyger 
marking a bear with a brightly- 
colored dye so that the animal 
can later be identified from 
an airplane. 

13 



ft 





During the half hour when the 
bear cannot move, biologists 
take measurements of its body 
(1), and clip a numbered tag to 
one of its ears (3). Photo 2 
shows a bear fitted with a collar 
that contains a dummy radio 
transmitter, similar to the trans- 
mitters that will enable scien- 
tists to study the travels of polar 
bears. 




*>>&# 



The Great Bear of the North (continued) 

The drug presented some problems too. The biologists 
needed to find a drug that would work quickly and still 
wear off fairly soon. They also needed a drug that would 
not harm the bears in any way. Although the perfect drug 
has not yet been developed, the scientists have found two 
that work fairly well. The drugs must be used with great 
care, though. An amount that would be correct for a large 
bear could kill a smaller one. So the scientists first estimate 
the size of a bear from the airplane, then load the syringe 
with the proper amount of the drug. 

Besides studying bears in Alaska, Dr. Flyger has hunted 
and tagged bears from a ship near the Svalbard Islands, 
north of Norway. Earlier, near the same islands, Dr. Martin 
Schein and a photographer took underwater motion pic- 
tures of a polar bear swimming. The pictures showed that 
the bear used only its front legs for swimming; its hind legs 
seemed to act as rudders, or steering devices. 

From Bear to Nimbus to Computer 

The biologists hope to trace the travels of polar bears 
by attaching radio transmitters to the animals. The trans- 
mitters would send signals that could be used to find an 
animal's location. Such animals as deer, raccoons, and 
grizzly bears have been tracked by radio. 
14 



So far no polar bear has actually been fitted with a radio 
transmitter. The biologists first had to make sure that a 
dummy transmitter, about the size and weight of a real 
one, could be held on a bear's neck in a special collar (see 
Photo 2). Now they must find a battery that will power the 
transmitter in the low temperatures of the Arctic. The 
transmitter must also be waterproof, since polar bears 
often swim long distances. 

Some time this year, the National Aeronautics and 
Space Administration (NASA) may launch a satellite 
called Nimbus that could help track polar bears. The main 
job of the instruments aboard Nimbus will be to gather 
information about the weather. But Nimbus could also 
receive radio signals from polar bears. The satellite's in- 
struments would store the information it receives. Later 
the information would be sent to ground stations, where 
computers would figure out the location of a bear several 
times each day. 

Polar bears might also be fitted with devices that would 
record the animals' heartbeat and rate of breathing. This 
information could also be sent to Nimbus, and eventually 
to computers on earth, by radio. Using methods like this, 
man may finally be able to understand the mysterious ways 
of the great bear of the north ■ 

NATURE AND SCIENCE 



The Land That 
Keeps Its Cool 

Living on the frozen earth is no problem 
—until it begins to melt! 

by Margaret E. Bailey 



■ The Arctic region has kept its cool for so long that scien- 
tists call the frozen earth there by a special name — perma- 
frost. Permafrost is a layer of earth that stays frozen all 
year long, year after year. The layer begins a few feet below 
the surface of the earth and extends downward 1 00 to as 
much as 2,000 feet in some places. It covers about five 
million square miles of the Arctic and surrounding areas 
(see map on page 2). 

Only the top few feet of this super-cool land ever "de- 
frost." Scientists call this the active layer, and it is so 
"active" that it causes a lot of trouble for people who live 
in the Arctic. 

Each summer the sun's heat melts the ice in the active 
layer, which softens into a thick, molasses-like mud called 
"slud," or "muskeg." Animals and vehicles get stuck in this 
slud, and roads and even airplane landing strips sink down 
into it. The icy permafrost under the slud acts like a sliding 
board, and the slud slithers and slips around on top of it. 
Anything caught in the slud slides along with it — including 
whole sections of highways, plants, animals, trucks, and 
houses. 

World's Biggest Deep-Freeze 

When the active layer freezes in the fall, even more 
serious trouble begins. After the summer thaw, the active 
layer is full of meltwater. When the temperature goes down 



below freezing once more, the active layer starts to re- 
freeze, from the top downward. 

As the water at the top of the active layer refreezes, it 
traps the unfrozen water between it and the permafrost. 
The trapped water has some air in it, and as the surface 
layer freezes, it expands and pushes the air into a smaller 
and smaller space. The air in turn pushes on the trapped 
water. If there is a weak place in the upper frozen layer, 
say a spot where a house stove has thawed the ice, the 
water may burst out through the ice. The water can fill a 
whole house, and when it freezes and expands, the ice may 
"explode" the house. Water freezing in the active layer also 
cracks highways and building walls as it expands and 
pushes them upward. 

Houses that tilt or slump are common sights in the 
Arctic. This is because the heat from a building can thaw 
the permafrost during the winter, and the softened ground 
under the building may sink or shift. Engineers have found 
that the only way to prevent this is to keep permafrost 
frozen. One way to do this is to support a building on steel 
columns above the ground. The layer of air between the 
building and the ground reduces the amount of heat that 
passes from the building to the ground (see diagram). 

Another way — much cheaper — is to put a layer of 
gravel between the building and the ground (see diagram). 

(Continued on the next page) 




A heated building sinks into the earth unless it is built so moving air can carry the heat away before it thaws the frozen soil. 

January 20, 1969 15 



The Land That Keeps Its Cool (continued) 

The gravel also keeps heat from the building from reaching 
the permafrost. The gravel may be carried away gradually 
by wind or water, though, and have to be replaced. 

Sometimes a refrigerating system is needed to make sure 
that the permafrost under a building keeps its cool. Pipes 
can be put into the ground under the building with their 



How Plants Survive in Permafrost Country 

There is little rain in permafrost country, but the melt- 
water in the active layer provides enough moisture for 
plants to sprout in the spring thaw. Trees grow in 
southern permafrost regions, but their roots can't go 
very deep. The trees often tilt in all directions as ex- 
panding ice pushes them up during the fall freeze. In 
the Arctic tundra (see page 2) there are no trees be- 
cause water remains frozen nearly all year. In winter 
the dry wind evaporates any available moisture, but 
some small plants escape its effects by dying down to 
their roots in the soil each winter and sending up new 
sprouts during each summer thaw. Other plants that 
can survive with little moisture also keep the tundra 
from being a total desert. 



tops exposed to the cold air outside. As air blows through 
the pipes, it keeps the ground under the building frozen. 
In the summer the pipes can be stopped up to keep warm 
air out. 

What a Way To Go 

Getting where you want to go can be a real problem in 
permafrost country, especially if you travel by road. When 
the soil and plants are removed from the active layer to 
build a road, the permafrost gets more heat from the sun. 




■ 

Trees are often tilted in different directions by frosf bo//s— 
pools of meltwater that collect at the bottom of the active 
layer and push the layer upward as the water freezes and 
expands. 

If the sun melts the permafrost, the road may cave in. 
Roads built on permafrost must be repaired constantly and 
often have to be abandoned. 

If a driver does manage to keep his car or truck out of 
the summer slud, he may not be so lucky in the fall freeze. 
The active layer does not all refreeze at the same time, and 
car wheels often break through a thin crust of new ice. If 
the wheels sink too far into the holes, the car may become 
stranded on the ice in the center of the road. In the late 
spring, summer, and fall, the best way to travel over perma- 
frost is to fly above it. 

Scientists believe that most of the permafrost formed 
when the climate was colder than it is at present. Within 
the past century, the earth's climate has been slowly warm- 
ing up. The Arctic permafrost appears to be melting back 
at its southern edges, and perhaps along its bottom surface. 
But it will be a long time in the future before men can stop 
seeking new ways to live and get around on this immense, 
deep-frozen land ■ 



PERMAFROST DOES A MAMMOTH JOB 



The large.ancient kinds of elephants called mammoths 
died out thousands of years ago. But it is not unusual 
to find the body of a mammoth with flesh, fat, hide, and 
hair still on it buried in permafrost. For many years no 
one could explain how the mammoths got buried in the 
permafrost that preserved their bodies. 

A possible explanation has been suggested by scien- 
tists who study how permafrost forms. Almost all of the 
mammoth remains have been found in frozen mud and 
clay from river floods or mud flows. It seems likely that 
old or weak mammoths may have sought protection from 
their enemies in shallow river beds and swamps, then 
died there. When floods came during the spring thaw, 



the mammoth bodies would be partly covered with clay 
and mud, which would help preserve them. Some 
mammoths apparently got stuck and died in slud, and 
that also protected their bodies. 

The remains of summer plants have been found in 
the preserved animals' stomachs, so the mammoths 
probably died in the late summer. The bodies would not 
have decayed much before the winter freeze set in. The 
following spring, flood waters would have covered the 
bodies with even more mud and clay. As this material 
gradually piled up higher and higher, it blocked the 
sun's heat from the deeper layers, which gradually be- 
came permafrost in the cold Arctic climate. 



Using This Issue . . . 

(continued from page 2T) 

In the igloos and sod-and-stonc 
houses, entrance passages are usually 
lower than the level of the floor inside. 
(Sometimes a sunken entry can't be 
built because the snow is not deep 
enough. Then the Eskimos add an 
entry hall like the one shown in the 
model on page 8.) The low entry is 
out of the wind. Cold air that enters 
the igloo is gradually warmed by heat 
from blubber lamps and by body heat 
given off from the Eskimos. As the air 
warms, it rises toward the top of the 
igloo. The air at the level of the raised 
sleeping platform (see photo on page 
8) may be 60° F. or warmer. 

Topics for Class Discussion 

• Why do your hands sometimes 
become numb and clumsy when ex- 
posed to the cold? One of the body's 
automatic responses to cold is to de- 
; crease the flow of blood to extremities 
such as the fingers. This reduces the 
amount of heat lost from the body. It 
also affects the muscles and nerves, so 
that the fingers don't move easily. The 
; circulation in an Eskimo's fingers 
picks up again very quickly after expo- 
• sure to cold. 

You might emphasize to your pupils 
that this characteristic of Eskimos is 
a physiological adaptation to the Arc- 
j tic. (The Wall Chart illustrates 
several cultural adaptations.) Scien- 
' tists believe that the body shape of 
! Eskimos represents a morphological 
[adaptation. Eskimos have shorter 
arms, legs, fingers, and toes than 
i people living in warmer climates. Be- 
I cause of this they have less skin sur- 
face area to give off body heat. Eski- 
imos also have an extra-heavy layer of 
body fat. (This might be considered 
:both a physiological and morphologi- 
cal adaptation.) Some scientists think 
; that the shape of the Eskimo face— 
(flattened, padded with fat, and having 
|a small nose— also has evolved through 

Ithe years to withstand the cold better. 

I 

(Further Reading 

• People of the Noatak, by Claire 
Fejes, Alfred A. Knopf, New York, 
1966, $6.95. Written for adults, this 
book tells of life in Eskimo villages 



where the old hunting life is still prac- 
ticed. 

Two good books for children are: 

• Arctic Hunters and Trappers, by 
Sonia Bleeker, Wm. Morrow & Co., 
New York, 1959, $2.95. 

• People of the Snow, by Wanda 
Tolboom, Coward-McCann, Inc., 
New York, 1957, $3.25. 

Animal Numbers 

If your pupils are unfamiliar with 
graphs, you may have to explain the 
ups and downs of the lynx skin num- 
bers shown on pages 1 and 1 1 . 

Emphasize that cycles are most 
common in simple communities, such 
as those in the Arctic and on isolated 
islands. The more plants and animals 
of different kinds a community has, 
the less subject to drastic change it 
will be. The most stable plant and ani- 
mal communities seem to be in the 
tropics, which has the greatest variety 
of life. 

To promote stability, and thus avoid 
outbreaks of pests and the disappear- 
ance of useful plants and animals, man 
should be trying to keep life on earth 
as varied as possible. However, exactly 
the opposite is happening. Man is 
speeding up the extinction of many 
species and simplifying communities 
by reducing the variety of life in them. 
Scientists are concerned that this will 
result in increasingly frequent erup- 
tions of crop diseases and pests. 

Brain-Boosters 

Mystery Photo. The cloudiness of 
the water is due to the presence of air 
bubbles. When water is under pressure 
in a plumbing system, the air in the 
water is completely dissolved. Once 
the water leaves the faucet, however, it 
is no longer under pressure, so the air 
comes out of solution and forms bub- 
bles in the water. As the air bubbles 
rise to the surface of the water and 
break, the water becomes clear again. 

The fizzing of soda pop is due to 
escaping carbon dioxide. The carbon 
dioxide will bubble out of solution 
least quickly when the soda pop is kept 
in a closed container in a cold place. 
Reducing the downward pressure of 
the gas above the soda pop (by opening 



January 20, 1969 



the bottle), warming the liquid, or dis- 
turbing it (by shaking or pouring), will 
cause the carbon dioxide to bubble out 
faster. 

What will happen if? If you can 

obtain a large jar (with cover) and a 
small fish, you can demonstrate that 
when the jar is turned upside down, the 
fish will remain upright. This is be- 
cause merely turning the jar upside 
down will not disturb the water sur- 
rounding the fish very much. (Don't 
keep the fish in the covered jar longer 
than a half hour or so.) 

If the fish were turned upside down 
by moving water, it would right itself 
immediately. You and your class can 
see how a fish reacts to moving water 
by rolling the closed jar along a table- 
top. This will set the water in motion. 
Another way to observe the effect of 
motion on a fish is to place the fish in a 
shallow bowl of water over the center 
of a phonograph turntable. (If the cen- 
ter spindle can't be removed, use a few 
wooden blocks to raise the bowl above 
the spindle.) How does the fish react 
when the turntable begins moving, or 
when it reaches a steady speed? (Make 
sure to center the bowl on the turn- 
table, or it may fly off when the table 
turns.) 

Can you do it? Probably no one will 
be able to break a round toothpick held 
as shown in the diagram merely by 
squeezing it between the extended fin- 
gers. It can be broken, however, by 
slapping the hand down hard on a desk 
or table. When the second and fourth 
fingers meet the desktop, they are 
stopped; the raised middle finger tends 
to keep moving downward. The extra 
force this motion gives to the middle 
finger should be sufficient to break the 
toothpick. Ask your pupils why Tun- 
ing at a stuck door may sometimes help 
to open it when pushing alone doesn't 
work. 

Fun with numbers and shapes. Path 
C would be the one made by a pebble 
caught in the tread of a bicycle tire. 
You can demonstrate this by making a 
large disc out of cardboard, cutting a 
hole near the edge where a piece of 
chalk can stick through, and rolling 
the disc along the chalk tray so the 
chalk can draw its path on the board. 
(Continued on page 4T) 

3T 



Using This Issue . . . 

(continued from page 3T) 

For science experts only. The girl 
was born in the southern hemisphere 
in December, January, or February. In 
the southern hemisphere these are 
summer months. She now lives in the 
northern hemisphere, where winter oc- 
curs during these months. 

With a flashlight and a classroom 
globe, you can demonstrate how the 
earth's tilt in relation to the sun helps 
cause seasonal variations in tempera- 
ture. In a darkened room, shine the 
flashlight at the globe as shown in the 
diagram. See whether any of the 



tt Y\,__V 

r 1 










pupils are able to observe that when 
the flashlight shines obliquely on a 
portion of the globe ("winter"), the 
light is distributed through a greater 
volume of air, and over a greater land 
area, than when the flashlight shines 
more directly on a portion of the globe 
("summer"). Absorption of the sun's 
heat by greater masses of land, water, 
and air helps to account for the lower 
winter temperatures. 

Just for fun. Pendulum bowling is 
fun. If your pupils investigated pen- 
dulums as suggested in "A Swinging 
Experiment" (N&S, Jan. 6, 1968), 
they are likely to begin by dropping 
the pendulum so it swings back and 
forth through the same arc. If the 
box "pins" are far enough apart and 
not in a straight line, the pendulum 
won't knock any more down after the 
first swing. Your pupils may discover, 
however, that giving the weight a side- 
ways push as it is released will make 
the pendulum swing in ever-changing 
paths, so a box that is missed on the 
first swing may be knocked down in a 
later swing. 

4T 




charts 



Prepared under the 
supervision of The 
American Museum 
of Natural History 



from 
nature and science 



Let your classroom walls help you teach with a completely new set of 10 Na- 
ture and Science Wall Charts. Reproduced from the pages of Nature and 
Science— and enlarged 300% in area— these Wall Charts cover a range of sub- 
jects that your science class should know about. 

For chalkboard, bulletin board, wall— for science exhibitions and displays— 
here are lasting sources of information that are always ready to catch (and 
educate) the wandering eye of any student. 



* all fully illustrated in vivid color 

* printed on durable, quality stock 

* each chart an abundant 22 by 34 inches 

* delivered in mailing tube for protection and storage 



Six Ways to Success — describes six 
ways in which plants and animals are 
adapted to insure survival of the species. 

Travel Guide to the Sun and Its Planets 

— depicts our solar system, showing rel- 
ative sizes of the planets, number of 
satellites, temperature, diameter, dis- 
tance from sun. 

The "Spirit" That Moves Things— ex- 
plains what energy is, where it comes 
from, and how it can change form. 

History in the Rocks — cross section of 
Grand Canyon shows how each geo- 
logical stratum was formed and illus- 
trates some representative fossils from 
each period. 

Spreading the Word — depicts how man 
has communicated information from 
one place to another through the ages. 



Visit to a Plant Factory — shows how 
green plants make their own food and 
how the food is transported to their 
parts. 

Rabbit Rollercoaster — illustrates the 
annual population cycle of the cotton- 
tail and describes why few rabbits live 
as long as a year. 

How Diseases Get Around — diagrams 
ways in which diseases arc spread and 
shows how vaccines protect against 
disease. 

Who Eats Whom — explains the ecol- 
ogy of the sea and some of the links in 
its "food chains." 

The Horse's First 55 Million Years- 
museum reconstructions in a time-line 
presentation illustrate the evolution of 
the horse. 



Imagine your pupils' excitement as you display a different chart each month 
of the school year. Order a complete collection of ten for only $7.50. 

To order, use postpaid order form bound into this issue. 



NATURE AND SCIENCE 



nature and science 

TEACHER'S EDITION 

VOL. 6 NO. 10 / FEBRUARY 3, 1969 / SECTION 1 OF TWO SECTIONS 

COPYRIGHT © 1969 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 

m N&S REVIEWS ► 

Recent Physical Science Books 
for Your Pupils 

by Fred C. Hess 



nature 

and science 



Questions About the Oceans, by 

Harold W. Dubach and Robert W. 
Taber (U.S. Naval Oceanographic Office 
Publications G-13, Superintendent of 
Documents, Government Printing Office, 
121 pp., 55 cents). One hundred ques- 
tions about oceanography are answered. 
The questions were raised by pupils and 
teachers visiting a science fair and are 
typical of many that would arise in your 
classroom. The answers are clear and 
direct, brief and to the point. While no 
attempt has been made to organize the 
questions by topic, both individually and 
collectively the answers to them make 
fascinating reading. Even the questions 
are useful. Oceanography is a new and 
exciting field of knowledge, and this little 
paperback provides a good introduction 
to it. 

When Nature Runs Wild, by Thomas 
P. Johnson (Creative Education Press, 
120 pp., $4.95), is a beautiful book deal- 
ing with the worst of man's natural 
enemies: earthquakes, volcanoes, land- 
slides, avalanches, floods, tsunamis, hur- 
ricanes, tornadoes, drought, forest fires, 
radiation, and pollution. It vividly de- 
scribes them and then explains what man 
can do about them. A section of experi- 
ments and projects dealing with these 
topics is included. A glossary, a bibliog- 
raphy of books and films, and an index 
round out a professional presentation 
that includes 150 well-selected photo- 
graphs and diagrams. Available also in 
paperback form at $3.95, this should be 
a most useful reference work in your 
earth science library. 

Dr. Fred C. Hess is a Professor of Physical 
Sciences at State University of New York 
Maritime College, Fort Schuyler, New York. 



The King's Astronomer: William 
Herschel,by Deborah Crawford (Julian 
Messner, 192 pp., $3.50), is a lively biog- 
raphy of the "father of modern as- 
tronomy." Miss Crawford deftly draws 
the reader into the Herschel household 
to relive with Sir William and the talented 
members of his family his 83 years of 
achievement. His early career in music, 
his abiding interest in astronomy, his 
solar system discoveries, his relation- 
ships with other astronomers, his con- 
ception of the "island universe" are all 
vividly presented. Both the scientist and 
his science are humanized. Many will 
like it simply because it is an interest- 
ing story well told. 

Famous Astronomers, by James S. 
Pickering (Dodd, Mead & Company, 128 
pp., $3.50). The stories of 10 astronomers 
are used to chart the development of 
astronomy from its infancy up to, but 
not including, the modern era. These 
biographies present the astronomical 
ideas of the Greek philosophers Aris- 
totle, Eratosthenes, and Hipparchus. 
Next, Ptolemy and his Almagest bring 
astronomy to its apparent death in 150 
A.D. The rebirth of the science in the 
16th century is portrayed through the 
stories of Copernicus, Tycho, and 
Kepler. Advancement into the 19th 
century is represented by biographical 
sketches of Galileo, Newton, and 
Herschel. All of these biographies are 
quite pleasant and would serve well to 
warm up and amplify those typically 
cold textbook biographical notes. 

UFOs and IFOs: A Factual Report on 

Flying Saucers, by Gardner Soule (G. P. 

Putnam's Sons, 192 pp., $3.49), is a rea- 

(Continued on page 3T) 



IN THIS ISSUE 

(For classroom use of articles pre- 
ceded by •. see pages 2T and 3T.) 

• Which Way is Down? 

By varying the positions of sprout- 
ing seeds, your pupils can discover 
whether plant roots always grow 
down. 

• How We Live in Flatland 

Have your pupils try to see this im- 
aginary two-dimensional world from 
a Flatlander's point of view. 

• Big Eyes on Space 

This Wall Chart shows how differ- 
ent kinds of telescopes work and 
tells why a telescope "sees" objects 
in space more clearly than your eye 
can. 

Trying to Take the Twinkle Out 
of Stars 

An astronomer tells about his ad- 
ventures and frustrations in sending 
balloon-borne telescopes into the 
stratosphere. 

Tale of the Torrey Canyon 

A detergent "cure" for oil on 
troubled waters made the Torrey 
Canyon shipwreck a threat to life in 
the sea. 

• Brain-Boosters 



IN THE NEXT ISSUE 

How a biologist explores life on a 
tiny Pacific isle . . . Winners in the 
Brain-Booster Mystery Object Con- 
test ... A Wall Chart showing how 
plants and animals are adapted for 
the renewal of life in springtime. 



USING THIS 

ISSUE OF 

NATURE AND SCIENCE 

IN YOUR 

CLASSROOM 



Which Way Is Down? 

This Science Workshop investi- 
gates the growth movements of plants, 
called tropisms. These movements can 
be either positive or negative; a plant 
or plant part may grow toward or away 
from the stimulus. For example, stems 
and leaves are positively phototropic 
(growing toward light) and negatively 
geotropic (growing away from the pull 
of gravity). Roots are negatively pho- 
totropic (growing away from light) 
and positively geotropic (growing to- 
ward the pull of gravity). 

These movements are controlled by 
hormones called auxins. The hormones 
may stimulate or inhibit growth, de- 
pending on their concentration and the 
part of the plant they are acting upon. 
As a root grows, auxin is concentrated 
most in the cells that are in its lower 
surface (see diagram). The auxin slows 
the growth of these cells, so root cells 
on the upper side grow comparatively 
longer. This causes the root tip to 
curve downward toward the center of 
the earth. 

For further investigations into plant 
tropisms, including phototropism and 



NATURE AND SCIENCE is published for The American 
Museum of Natural History by The Natural History 
Press, a division of Doubleday & Company, Inc., fort- 
nightly September, October, December through March; 
monthly November, April, May, July (special issue). 
Second Class postage paid at Garden City, N.Y. and at 
additional office. Copyright © 1969 The American 
Museum of Natural History, All Rights Reserved. Printed 
in U S A Editorial Office: The American Museum of 
Natural History, Central Park West at 79th Street, 
New York, N.Y. 10024. 

SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester 
per pupil, $1.95 per school year (16 issues) in quanti- 
ties of 10 or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's 
edition $5.50 per school year. Single subscription per 
calendar year (17 issues) $3.75, two years $6. Single 
copy 30 cents. In CANADA $1.25 per semester per 
pupil, $2.15 per school year in quantities of 10 or more 
subscriptions to the same address. Teacher's Edition 
$6.30 per school year. Single subscriptions per cal- 
endar year $4.25, two years $7. ADDRESS SUBSCRIP- 
TION correspondence to: NATURE AND SCIENCE, The 
Natural History Press, Garden City, N.Y. 11530. Send 
notice of undelivered copies on Form 3579 to: NATURE 
AND SCIENCE. The Natural History Press, Garden City, 
N.Y. 11530. 



hydro- (water) tropism, see the book: 
Discovering Plants, by Richard M. and 
Deana T. Klein, Natural History Press, 
Garden City, New York, 1968, $4.50. 

Activity 

Set up three jar lids with soaked 
(imbibed) seeds as described in the 
text of the article. Leave one as a con- 
trol with which to compare the others. 
Every three or four hours, rotate the 
other lids, turning one halfway around, 
the other about a quarter-turn. Mea- 
sure the growth of the root and stem of 
each sprout in all three lids. Do the 
control beans grow any faster than the 
rotated ones? 



CUTAWAY VIEW 
OF GROWING ROOT 



CELLS GROW 
LONGERON 
UPPER SIDE 




AUXIN INHIBITS 
CELL GROWTH 
ON LOWER SIDE 



Life in Flatland 

This unusual and amusing article 
will surely stretch the imaginations of 
your pupils. It offers more than enter- 
tainment. Hopefully, your pupils will 
come away with an appreciation of the 
meaning of three-dimensional space 
and, perhaps, a respect for the limita- 
tions of their particular view of the 
world. 

Topics for Class Discussion 

• How does the jog in Flatland help 
the inhabitants recognize one another? 
It is their only way of perceiving depth. 
Can your pupils think of paintings in 
which the artist created the illusion of 
distance by making mountains or trees 
in the background hazy? 

• What would happen if the atmos- 
phere in Flatland were to clear up? 
The far edges of figures would appear 
as close as the near edges, giving every- 
thing the appearance of a straight line. 



Can perspective, which is another way 
artists depict space on a two-dimen- 
sional surface, be employed in Flat- 
land? No, because the edges seen in 
Flatland have no thickness that can 
be diminished. 

• Does everyone in "Spaceland" see 
things from the same point of view? 
Would an ant's view of the world be 
the same as that of a ten-year-old boy 
or girl? How might the world look to 
a baby in a playpen, or to a flagpole 
sitter? Can your pupils conceive of 
what it would be like to be blind? 

Activities 

• To further demonstrate the peculi- 
arities of a world without height, have 
your pupils look at a photograph in a 
book. What happens to the image as 
they bring the edge of the book up to 
eye level? At what point does the pic- 
ture become unrecognizable? Would 
living in Flatland be anything like 
looking at a room through the crack 
under the door? 

• Have your pupils try to imagine a 
world without weight, or time, or 
death, or taste, and so forth. For in- 
stance, in a world without light, would 
we still have artists, or writers, or be 
able to drive cars? How would we 
have to change our ways of doing 
things? With such a discussion as a 
starting point, encourage your students 
to write a fantasy of their own. 






Big Eyes on Space 



2T 



You might have each pupil look 
through a small telescope (or one side 
of a binocular) at an object across 
the room; then, when the object is in 
focus, open the other eye and compare 
how the object appears with and with- 
out the help of the telescope. They 
can see that the object appears bright- 
er and "sharper," as well as larger, 
through the telescope. 

Some may suggest that perhaps the 
telescope eyepiece "magnifies" the 
brightness of the object as well as its 
size. This possibility can be investi- 
gated by holding a small magnifying 
glass over part of a shiny object, such 
as a spoon. Does the enlarged image 
seen through the lens appear as bright 
(Continued on page 3T) 

NATURE AND SCIl V< / 






Mfti 



VOL 6 NO. 10 FEBRUARY 3. 1969 



nd science 



Women are straight lines? 
Yes, that is. . . 

HOW WE LIVE 
IN FLATLAND 



see nape 4 




Will telescopes in space 
replace those on earth? 

see pages 8 and 1 

Big Eyes on Space 

and 

Trying To Take the 

Twinkle Out of Stars 




nature and science 

VOL. 6 NO. 10 / FEBRUARY 3, 1969 
CONTENTS 

Which Way Is Down?, by Nancy M. Thornton 
How We Live in Flatland 
What's New?, by B. J. Menges 
Big Eyes on Space 

Trying To Take the Twinkle Out of Stars, 
by Robert E. Danielson 
14 Tale of the Torrey Canyon, 

by Susan J. Wernert 
16 Brain-Boosters, by David Webster 



PICTURE CREDITS: Cover, photo courtesy of Grumman Aircraft Engineering 
Corp., drawing by Joseph M. Sedacca; pp. 2-6. 8-9, 15-16. drawings by Graphic 
Arts Department, The American Museum of Natural History; p. 7, Lerner 
Marine Biological Laboratory; pp. 8-9, top: Yerkes Observatory photo, other 
photos from the Mount Wilson and Palomar Observatories; p. 10, NASA; p. 11, 
Project Stratoscope of Princeton University sponsored by NSF, ONR, and 
NASA; pp. 12-13, Barbara Schwarzschild; p. 14, United Press International; 
p. 15, photos by N. A. Holme; p. 16, photo by David Webster. 



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SENTING THE AMERICAN MUSEUM OF NATURAL HISTORY: FRANK- 
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■ You plant a seed in soil and a few days later new lei v 
are reaching toward the sky. Below ground, out of si # 
you know that roots are growing deep into the soil. 

Do you suppose you could "fool" a seed into sent ii 
roots up, instead of down? Does the position of a spno, 
ing seed affect the direction its roots and leaves grow? 

You can find answers to these questions by setting up 
simple investigation using Red Kidney, Pinto, or anoth< 
kind of garden bean (available at garden or hardwaj 
stores). You can also use dried seeds that are used fc 
baking beans. These can be found at any grocery stor 

Soak Some Seeds 

Soak several dozen beans in warm (not hot) wate 1 
They should be covered with two inches of water for 3 
least four hours and for no longer than 12 hours. 

Notice how much the seeds swell. Seeds also do th. 
when they are planted in soil. Of course, if the ground i 
very dry, it takes longer for this swelling to take place 
This process of soaking up water is called imbibition 
Farmers sometimes speed the start of seedlings by soakin; 
seeds before planting them. 

After imbibition has taken place, peel off the outer coa 
of one seed to see what is inside. The outer coat may hav< 
already split off. The two fat halves are called cotyledon 
(see Diagram 1 ). They provide stored food for the plan 1 
until it is able to make its own food by the process called 
photosynthesis. This process goes on in a plant's leaves. Ij 
requires energy from the sun, so it cannot begin until sunj 
light reaches the leaves. If there were no stored food in thd 
cotyledons, the young plant would die before it could 
reach the ground's surface. 

Between the cotyledons you will see a small pointed 
object at one end of the bean. This is called the hypocotyl 
(see Diagram 1). The tip of the hypocotyl (called the 
radicle) eventually forms the main root of the bean plant, 




m 



"ing some bean seeds, jar 
;, and cotton, you can find 
out if a sprouting seed always 
"knows" . . . 

Which 



way is 
down? 



,i your seeds grow, be sure to watch the direction of 
iicle growth. 

sThe tiny object inside the cotyledon, which looks like 
,o tiny, folded yellow leaves, is the plumule. When the 
7 tyledons emerge from the ground, the plumule grows 
ge and turns green. The plumule is the beginning of the 
tves, stems, and buds of the bean plant. 
; You might wonder what a seed looks like before imbibi- 
n. Use a dull knife to split a dried seed. How does it 
mpare with a seed after imbibition? 



e the Light 

The seeds will start to sprout soon after they soak up 
ne water. Take a cotton wad the size of a large marsh- 




TAPE OR TIE 
PLASTIC IN BACK 



mallow and wet it so that it js very damp, but not drippy. 
Flatten it and put jt inside of a lid from a wide-mouthed 
jar. Place two seeds, facing the same way, on the cotton. 
Wrap some clear plastic (such as Saran Wrap) over the 
open side of the lid. The cotton should be thick enough to 
hold both seeds firmly against the plastic. Stretch the plas- 
tic tightly in back of the lid so that it is flat across the front 
and tape it firmly in place (see Diagram 2). With a sharp 
pencil, punch four or five small holes in the plastic around 
the seeds (to let air in). 

Diagram 3 shows how to put the seeds inside of several 
different lids. Maybe you can think of other ways to place 
your seeds. 

Now prop the lids against a wall or window so that they 
are upright, facing the light. Beans grow best if they are 
in plentiful light and are at a temperature between 70° and 
85° Fahrenheit. Don't put the lids against a window if the 
weather is unusually hot or cold. 

Start watching for hypocotyls and radicles to sprout 
from the beans. Which direction do they grow? Do they all 
grow in the same direction? 

Perhaps you would like to try the same sort of investi- 
gation with other kinds of seeds. Smaller kinds of seeds 
should not be soaked as long. You might also try the same 
thing with "eyes" of potatoes. Cut each "eye" so that there 
is an attached piece of potato, about the size of a marble. 

Do you think that farmers must worry about how they 
place their seeds in the ground when they plant them? 

—Nancy M. Thornton 



INVESTIGATION 



How well are radicles able to change their directions 
of growth? Set up two lids with spaked seeds as you 
did before. After the radicles appear, turn one lid 
halfway around, like a doorknob. Leave the other lid 
alone. Then watch the growth of the radicles every 
hour or two. What happens? How soon do you notice 
changes? 



3. 



"\ 



incurved side 
facing cotton 




Which way do the roots grow when you place bean seeds 
in these positions? The dots on the beans show the location 
of their incurved sides. 



WHERE ALL REORLE ARE GEOMETR\C/\\_ ¥\GW^S> 
A/VD WOMEN ON THE MOVE ARE VE.RY DNUC^ROV^^ 



ADAPTED BY ROY A. GALLANT 



In 1884, an English clergyman and school head- 
master named Edwin A. Abbott wrote an amusing 
book with the title Flatland. The people in his story- 
are geometrical figures — triangles, squares, penta- 
gons, and so on. They live in a world of two dimen- 
sions, and to understand how they live as flat figures 
on a flat surface will make you do some hard think- 
ing. You will have to leave your Spaceland world of 
three dimensions and imagine you are a Flatlander 
in order to see the world from their point of view. 



■ I call our world Flatland, although that is not its real 
name. Perhaps the word "Flatland" will help you, who are 
lucky enough to live in Spaceland, to understand some- 
thing about our people. 

Imagine a great sheet of paper on which are Triangles, 
Squares, Pentagons, Hexagons, and other figures. Imagine 
also that these figures are free to glide about on the surface 
of the paper, but they do not have the power to stand up, 
rise above, or sink below the paper. They are very much 
like shadows — only they are hard and have bright edges. 
Oh, how difficult it is to describe all of this to you. 

You who live in Spaceland would find it easy to tell a 
Square from a Triangle. All you would have to do is look 
"down" on the figures. But in Flatland there is no "down," 
no "up," no such thing as "depth." Our people would not 
know what you meant if you used the expression "solid" 
object. In Flatland, a Square and a Triangle appear very 
much the same to us. They appear as Straight Lines. In 
fact, in our world everything appears to us as Straight 
Lines. Let me try to explain. 

Place a penny on a table and lean over it, looking down 
upon it. It will appear as a circle (see diagram). But now, 
move back to the edge of the table and gradually bring your 



This article has been adapted from parts of the book Flatland, by 
Edwin A. Abbott, available in paperback edition for $1 from Dover 
Publications, Inc., 180 Varick Street, New York, N.Y. 10014. 



eyes down level with the penny. Half-way down you see 
an oval; then, when your eyes are level with the edge of 
the penny, you see a Straight Line. Perhaps now you are 
beginning to understand how we see things in Flatland. 

PENNY 




G 



'■";i !i!r l '"l 



SEEN FROM EDGE-ON 



SEEN FROM 
HALF-WAY DOWN 



SEEN FROM ABOVE 



The same thing would happen if you took an edge-on 
view of a Triangle, Square, or any other figure. It ceases 
to appear as a figure and to your eye is a Straight Line. 

The inhabitants of Flatland are all figures, such as Tri- 
angles, Squares, and so on. But more about them in a mo- 
ment. I would like to finish making my point about how we 
see each other. Imagine that you are a Flatlander and that 
a Circle friend, or a Triangle friend, is coming toward you. 
What do you see? Since there is no Sun in Flatland, or any 
kind of light that casts a shadow, we have none of the helps 
to sight that you have in Spaceland. 

As your Flatlander friend comes closer to you, you see 
only a straight line. Imagine a yardstick, held flat and at 
eye level, moving toward you through your Spaceland air 
from the far end of a long corridor. The closer it floated 
toward you, the longer it would appear to grow. In the 
same way, as your Flatland friend approaches you, his line 
appears to become longer. And as he leaves you, it be- 
comes shorter. All the while he looks like a Straight Line — 
be he Triangle, Square, Pentagon, Hexagon, or Circle. A 
Straight Line he looks, and nothing else. 

At first thought you might wonder how we are able to 
tell one friend (a Square, say) from another (a Pentagon) . 

The People of Flatland 

As I said earlier, in Flatland there is no such thing as 
"up," "down," or "depth." In Spaceland, you say that a 

NATURE AND SCIENCE 



friend is so many feet and inches "tall." In Flatland, we 
cannot measure ourselves in height, only in length. A full- 
grown Flatlander may be as long as about 1 1 inches. 

All our women are Straight Lines (see diagram). 

Our soldiers and laborers are Triangles with two equal 
sides about 1 1 inches long. Their third side, or base, is 
rather short — often not more than half an inch, sometimes 
only a quarter inch. Soldiers and laborers are so very 
pointed that sometimes it is hard to tell them from women. 
A woman is a one dimensional figure, for she is all length. 

Our middle class citizens are also Triangles — but each 
of their sides is the same length. 

Our professional people are Squares; or sometimes they 
are five-sided figures called "Pentagons." 

Next above these come the nobility, who have several 
shapes. The lowest in rank are six-sided figures, or "Hexa- 
gons." People higher in rank have more than six sides and 
are called "Polygons." Some people have so many sides, 
and each side is so short, that it is hard to tell them from a 
Circle. The Circle, of course, is the highest rank of all. 

Our Dangerous Citizens 

A Spacelander reading this might well think that the 
soldiers are the most "dangerous" members of Flatland, 
since they are highly pointed Triangles. Imagine bumping 
into a soldier at high speed. His sharp point could be very 
painful. Actually, women are much more dangerous — for 
they are all point, at least at their two ends. To add to the 
danger, they can make themselves all but invisible at will. 
A few words will make this clear. 

Place a needle on a table. Then, with your eye on the 
level of the table, look at the needle sideways. You see the 



whole length of it. But look at it end-on and you see noth- 
ing but point. It has become nearly invisible. It is just so 
with a Flatland woman. When her side is turned toward us, 
we see her as a Straight Line. When she faces us, we see her 
only as a bright point; and when she walks away from us, 
we see nothing but a very dim point. 

If running into a soldier produces a gash, imagine the 
danger of running into a woman! It means instant death. 
In some of the states of Flatland there is a law saying that 
women must not walk or stand in any public place without 
keeping their backs moving from right to left. To any one 
approaching a woman from the front or rear, this motion 
makes the woman visible as a line constantly becoming 
longer and shorter. 

In one Flatland state, women are thought to be so 
dangerous that the following law was written: Any Female 
suffering from St. Vitus's Dance, fits, violent sneezing, or 
any disease bringing on violent motions which she cannot 
control shall be instantly destroyed. 

How We Recognize One Another 

You in Spaceland, who can see a whole circle, who can 
actually see an angle — how can I make clear to you the 
trouble we in Flatland have recognizing one another? 

Recall what I told you earlier. All people in Flatland, 
no matter what their shape, to our view appear as a Straight 
Line. Fortunately, in addition to seeing, we have another 
way of recognizing one another. In a manner of speaking, 
we "shake hands," but it is really more like touching one 
another. If a Triangle and a Square are introduced and 
touch one another, each can tell the shape of the other. But 

(Continued on the next page) 



STRAIGHT 
LINES 



EQUAL-SIDED TRIANGLES 



WOMEN 



LONG 
TRIANGLES 




MIDDLE CLASS 
HEXAGONS 





SOLDIERS 



NOBILITY 



SQUARES 



PENTAGONS 




1 PROFESSIONAL PEOPLE • 

POLYGONS CIRCLES 







HIGHEST RANK 



February 3, 1969 



How We Live in Flatland (continued) 



this becomes harder to do with people who have many 
sides. Imagine the difficulty of telling a 20-sided Polygon 
without touching the person all the way around! 

Even though each Flatlander appears to any other Flat- 
lander as a Straight Line, still we can tell a Triangle from a 
Pentagon by sight. The reason we are able to is because 
there is nearly always fog in Flatland. Let me explain by 
giving you an example: 

Suppose I see two people coming toward me and I want 
to know what shape they are. One is an Equal-Sided Tri- 
angle, and the other is a Pentagon. I see the Triangle as a 
Straight Line A,B,C (see diagram). The mid-point B will 
be bright because it is nearest to me, but on either side — 
from B to A, and from B to C — the line will shade away 
rapidly into dimness because of the fog. So point A and 
point C, which are the Triangle's rear portions, will be 
very dim indeed. 

I see the Pentagon also as a Straight Line, D, E, F. As in 
the case of the Triangle, I see the mid-point (E) of the 
Pentagon as a bright point. As I saw points A and C of the 
Triangle dimly because of the fog, I also see the Pentagon's 
points D and F dimly, because of the fog. But I see the 
Pentagon's far points less dimly because its sides do not 
go so deeply into the fog as the Triangle's sides do. 



c B A 

THIS IS WHAT I SEE 



HOW I SAW THE SPHERE AS HE ROSE FROM MY SIGHT. 

HIS CIRCLE BECAME SMALLER AND SMALLER, 

UNTIL FINALLY HE VANISHED. 





HOW I SEE THE TRIANGLE 
D 





FED 
THIS IS WHAT I SEE 



HOW I SEE THE PENTAGON 

Recognizing each other by sight is not always easy. Sup- 
pose, for example, that my neighbor's son, who is a young 
Triangle, approaches me. But instead of presenting me 
with one of his angles, he happens to present one of his 
sides to me. I must then ask him to turn around, or I my- 
self, have to edge my eye round him in order to see his 
shape. If I see him only from the side, I cannot tell if he is a 
Straight Line, in other words, a Woman. 

A Visitor from Spaceland 

Perhaps you have been wondering how I, an inhabitant 
of Flatland, am aware of your Spaceland, and have found 
the words to describe our world to you. 




One evening — it was the last day of the 1999th year of 
our era — I was sitting in my study and felt a Presence in 
the room. A stranger suddenly appeared, as out of no- 
where. I touched him and found him to be the most perfect 
Circle I had ever met. Clearly he was from another land, 
for he also talked of a world of three dimensions, meaning 
a world of length, width, and height. 

Try as he did, the Stranger could not make me under- 
stand by words alone what he meant by "height." It is 
beyond our experience in Flatland. Finally, he said, "Now, 
sir, listen to me. 

"You are living on a vast level surface, without ever ris- 
ing above it or falling below it. I am not a flat figure, but a 
Solid. You call me a Circle. Actually I am many Circles of 
different size, but you can see only one of my circles at a 
time because you have no power to raise or lower your eye 
out of Flatland. In Spaceland I am known as a Sphere — a 
solid object. 

"Now prepare for proof positive of the truth I speak. 
See now, I will rise. The effect upon your eye will be that 
my Circle will become smaller and smaller till it dwindles 
to a point and finally vanishes." (See diagram.) 

There was no "rising" that I could see, but he grew 
smaller and smaller and finally vanished. I winked once or 
twice to make sure that I was not dreaming. But it was no 
dream. For from nowhere came a hollow voice: "Am I 
quite gone? Are you convinced now? Well, now I will 
gradually return to Flatland and you shall see my Circle 
become larger and larger." 

It was through that action, and others performed by the 
Sphere, that I came to know about the wonders of Space- 
land. It is now many years since that visit from the 
Stranger, and I am in prison, where I am to remain for the 
rest of my life. 

I tried to tell our people about Spaceland, but they 
would not believe me. It was "dangerous" talk, they said, 
for the wisest among our Flatland thinkers say that there 
are only two dimensions — length and width. Perhaps 
someday, someone else from Flatland will learn the truth 
of Spaceland, as I have. Perhaps, also, that person will suc- 
ceed in enlightening our people, where I have failed ■ 

NATURE AND SCIENCE 



i 



VHAT'S 
NEW 





by 

B. J. Menges 

Gold-coated airplane windows 

may seem like a publicity stunt, but they 
aren't. The gold coating could make the 
planes safer by preventing ice from form- 
ing on the windshield and blocking the 
pilot's vision. Gold's high ability to con- 
duct electricity makes this possible. 

The gold is heated until it melts, then 
boils and turns to vapor. Then it is ap- 
plied to the window glass, where it cools 
and hardens into a film about two bil- 
lionths of an inch thick. The film is so 
thin that it's transparent, but it's thick 
enough to carry an electric current. Dur- 
ing high-altitude flight, an electric 
current is sent through the coating. This 
heats the window enough to keep it from 
icing up even at temperatures as low as 
-65° F. 

The search continues for ways to 
treat virus diseases. Few drugs have any 
effect on viruses. But scientists have 
found that the body already contains a 
defense against viruses — a protein sub- 
stance called interferon. Interferon seems 
to help a person to recover from a virus 
infection, but the body doesn't produce 
enough of it to cure the illness quickly. 
Researchers at the National Institute 
of Allergy and Infectious Diseases, in 
Washington, D.C., have now found a 
man-made substance that makes the body 
produce more interferon faster. When 
rabbits infected with a virus-caused eye 
disease were treated with the substance, 
the amount of interferon in each rabbit 
increased enough to cure the disease 
rapidly. Experiments are now planned to 
find out whether this treatment can help 
cure humans of virus diseases such as in- 
fluenza and some forms of encephalitis. 

Sharks aren't so bad, suggests Dr. 
Perry W. Gilbert, a Professor of Zoology 
at Cornell University, in Ithaca, New 
York (see photo). After more than a 
decade of studying these fishes, he re- 



ports in BioScience that the dangers of 
their attacks on man are overrated. 
There are fewer than 100 shark attacks 
a year throughout the world, and only 
about half of them cause death. In con- 
trast, bee stings kill about 150 people a 
year in the United States alone. 

Furthermore, says Dr. Gilbert, sharks 
are of real value to man. Their meat is 
widely used as food in Japan, Australia, 
and Mexico. Their skins are made into 
high-quality leather that's stronger than 
pigskin or cowhide. And their bodies are 
being used in disease studies that promise 
to benefit man. 

A twin trip to Mars is planned by the 
United States for 1971. Two spacecraft 
are to be launched in May of that year, 
go into orbit around Mars in November, 
and stay there for at least three months. 
The orbit of one spacecraft will cross the 
Martian equator at an angle of 60 de- 
grees. As Mars rotates, this spacecraft 
will keep passing over different parts of 
the planet, so that it will be able to ex- 
amine about two-thirds of the Martian 
surface. 

The other spacecraft will pass almost 
over the planet's poles, getting a good 
look at the white polar caps, which are 
believed to be ice crystals. The craft may 
also view the two moons of Mars. Infor- 
mation sent to the earth by the two space- 
craft could lay the groundwork for an 
unmanned landing on Mars in 1973. 

Warmer sheep are the goal of scien- 
tists in Scotland. They hope to develop 
sheep that can stay warm in cold weather. 



Among sheep now in Scotland, some can 
stand the cold far better than others. The 
scientists will male the cold-resistant 
sheep, and from their offspring will select 
and breed those sheep that are hardiest 
in cold weather. Carried out over many 
generations, this process may produce a 
new breed of "cold-weather" sheep. 

Cold-hardy sheep would be valuable 
not only in Scotland, but also in Aus- 
tralia, where rain and cold kill many 
sheep after they are shorn, and in the 
Soviet Union, where sheep must now be 
kept indoors to escape the intense cold. 
Sheep farming could even become pos- 
sible in areas of the world that are too 
cold for existing breeds. 

A curtain of air bubbles can help to 
keep pollution away from beaches. Such 
a curtain has been tried out at a bath- 
ing beach in Stamford, Connecticut, that 
had been ruined by pollution. Pipes were 
placed under the water, surrounding the 
swimming area. When compressed air 
was released through tiny holes in the 
pipes, it created a barrier of bubbles in 
the water that kept out oil, garbage, bot- 
tles, and other wastes. Inside the bar- 
rier, another pipe released chlorine to 
purify the water. 

This method could be useful in keep- 
ing swimming areas clean until the 
sources of pollution can be eliminated. 
Bubble curtains have already been used 
to solve other problems. They can keep 
ice from forming around ships at anchor. 
They have also been used in the Nether- 
lands and in Norway to prevent salt wa- 
ter from entering fresh-water waterways. 



This photo shows Or. 
Perry W. Gilbert exam- 
ining a mako shark at 
the Lerner Marine Lab- 
oratory, a field station 
of The American Muse- 
um of Natural History 
located in Bimini, in the 
British West Indies. 




February 3, 1969 




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Astronomers hoped to get 
their first really clear view of 
the stars through telescopes 
lifted high in the earth's 
atmosphere. An astronomer 
who helped send up the 
telescopes describes the 
difficulties that arose in . . . 

Trying to 

take the 

twinkle 
out of 
stars 

by Robert E. Danielson 

— *— 



-*- 



-*- 



-*- 



i 
-*- 



-¥- 



I 
-*" 

I 



At lift-off, Stratoscope 2 hangs about 700 feet below its 
launch balloon. The slim white tube beneath the launch: 
balloon is the main balloon, which inflates with expanding; 1 
helium from the launch balloon as they rise through thinner' 
and thinner air. Under the main balloon are the parachutes: 
that return Stratoscope to earth. The photo below shows 
Stratoscope 2 on its mobile launch pad. 







'.»• 




r*Jt,\ . t 




■ "Twinkle, Twinkle, Little Star" is a delightful song, 
but not to astronomers, who have long wanted to see the 
stars as they really are— without any twinkle at all. 

The rapid dimming and brightening of starlight that 
we call "twinkling" is caused by disturbances in the "sea 
of air" that starlight must travel through to reach our tele- 
scopes near the "bottom" of that "sea." ( See "Discovering 
an 'Ocean' from the Bottom," N&S, November 11, 1968.) 

Air masses of different temperature and density are 
continually moving around in the atmosphere, changing 
the amount of starlight passing through them and "bend- 
ing" the rays of light in different directions. This makes 
the stars seem to twinkle, and— even worse for the as- 
tronomers—it blurs the images of stars seen through a 
telescope. Putting telescopes on mountain tops, above part 
of the earth's atmosphere, helps a little— but not enough. 

View from the Top 

Dr. Martin Schwarzschild, a Professor of Astronomy 
at Princeton University, and I thought we could solve this 
problem if we could send a telescope high enough in the 
sky. So about 1 years ago we sent a telescope up 80,000 
feet with a balloon. There in the upper atmosphere, called 
the stratosphere, the thin air did not blur the telescope's 
view of space. A camera on the telescope snapped the 
sharpest pictures ever taken of sunspots (see photo). 

This balloon telescope, called Stratoscope 1, was so 
successful on its seven flights that we planned to send up a 
balloon carrying a telescope that was three times more 
powerful— Stratoscope 2. We wanted to measure the 
amount of heat given off by Mars, hoping to find evidence 
of life on that planet. 

The first launch of Stratoscope 2 was on March 1 , 1963. 
We controlled the telescope by sending radio signals to 
it from the ground. A television camera on the telescope 
sent pictures to our TV sets of what the telescope "saw." 
This flight was not perfect, though. The radio signals from 
the telescope were weak, and the instrument that was 
supposed to measure heat rays from Mars did not work 
as well as we expected. We found no evidence for or 
against life on Mars, but we did learn more about the 
planet's atmosphere. 

We launched the second flight of Stratoscope 2 nine 
months later. We had tried very hard to correct the mis- 
takes in the first flight, and we had succeeded. The entire 
flight worked perfectly! We measured the amounts of heat 
coming from the moon, Jupiter, and several stars, and 
learned a great deal more about these objects. 

After this successful flight, we added more equipment 



Dr. Robert E. Danielson is a Professor of Astronomy at Princeton 
University, in Princeton, New Jersey. 

February 3, 1969 




Stratoscope 1 took the 
sharpest pictures yet 
made of sunspots. The 
one shown here is about 
15,000 miles across — 
nearly twice the earth's 
diameter. Sunspots ap- 
pear dark only because 
they are somewhat cooler 
than the surrounding parts 
of the sun's surface. 



so the telescope could take very sharp photographs. Strato- 
scope 2 was much more complicated now. The motors that 
turned the telescope to point at different objects had to 
work 100 times better. The telescope's focus had to be 
100 times sharper. Also, we did not want the telescope to 
change the temperature of the air around it in the strato- 
sphere. Temperature changes would cause the air to move 
and blur the images. So the entire telescope had to be at 
nearly the same temperature, and this temperature had to 
be close to the temperature of the air at 80,000 feet— 
about 67 degrees below zero Fahrenheit! 

When the telescope reached the stratosphere, it would 
have to cool off before we could start taking pictures. 
The problem was that we knew some parts of it would cool 
more slowly than others. In fact, we found that the tele- 
scope's mirror, which was 36 inches in diameter, cooled 
so slowly that we would have to cool it before the tele- 
scope was launched. 

Cooling It 

It was not too difficult to cool the mirror before launch- 
ing, but it was hard to keep it from frosting over in the 
humid air at the launch site— the National Center for At- 
mospheric Research Balloon Flight Station at Palestine, 
Texas. We kept the mirror sealed in a very dry enclosure 
and planned to open it only after the balloon was all the 
way up. 

By early December 1964, all the preparations for the 
third flight of Stratoscope 2 had been made. A refrigerator 
kept the mirror cold. The day after we were ready, the 
winds were low enough to inflate the balloon with helium 
gas. But the tubes that carried helium to the launch balloon 
were 50 feet too short. Three days later we were ready to 
try again, but the weather was cloudy for several days. 
Finally, clear weather was forecast. We inflated the bal- 
loon and were ready to launch it, when the wind suddenly 
became much stronger. The launching crew struggled with 
all their might, but they could not prevent the balloon 
from acting like a gigantic sail. Disaster struck. The 

(Continued on the next page) 

11 



Trying To Take the Twinkle Out (continued) 

delicate stratoscope was pulled apart by the sudden force 

of the wind on the balloon. 

It took seven months of hard work before we were ready 
to launch again— in July 1965. The weather on the launch 
date was fine, but we had to cancel the flight because the 
balloon leaked! A new balloon was ready three days later, 
but we had to wait out thunderstorms that lasted for nine 
days. On the tenth day, Stratoscope 2 was finally launched. 

While the balloon went up, we checked the television, 
radio, camera, and other equipment that was operated by 
remote control from the ground. Everything was working 
perfecUy. It looked as if our years of work were going to 
pay off. 

We were soon disappointed, though. When the balloon 
reached its high point, we tried to move the telescope by 
radio command. But the latch that held the telescope 
tube upright was jammed and would not let go. We finally 
had to give up and return the instrument to earth by letting 
some of the helium out of the balloon. 

We examined the telescope very carefully to try to 
learn why it had jammed. We found out that the jammed 
latch had been caused by a failure in the device that kept 
frost off the mirror during launching. 

Try, Try Again . . . 

We were a little discouraged by this second failure, 
but we got ready to try another launch. The faulty device 
was replaced and Stratoscope 2 was ready for launching 
again on April 19, 1966. But it began to rain and there 
was a bad flood near the balloon base. We were not able 
to inflate the balloon until May 8. Then to add to our 
troubles, the balloon leaked again! It was May 14 before 
we finally launched it. 

Everything worked perfectly after the balloon was up— 
until it came time to unlatch the telescope. It was jammed 
again! Hadn't we found what went wrong on the last flight? 

The answer became clear during the next few days. 
The telescope had jammed for a completely different 
reason than before. As the stratoscope rises, very tiny steel 
balls— called ballast— arc dropped to lighten the balloon 
so it will rise faster. One of the four ballast containers 
did not empty, and this made the telescope tilt. The tilt 



This photo of Stratoscope 2 undergoing tests shows how it 

appeared "at work." The fat cylinder at the left is 

the telescope tube, with a 36-inch curved mirror at the 

bottom end to collect light from distant objects. A flat mirror 

inside the tube reflects the light out through the side 

of the tube to a camera and other instruments 

on the "arm" at the right. 

12 



caused a small device to block the latch on the telescope 
tube. 

So a chance series of events had caused our third failure. 
But was it just chance, or had the telescope become so 
complicated that it had little chance of working? A group 
of engineers from the National Aeronautics and Space 
Administration's Marshall Space Flight Center, in Hunts- 
ville, Alabama, was called in to go over our project. 
These engineers decided that many important parts of 
Stratoscope 2 would have to be improved before we could 
be sure that it would work each time. 

The engineers who had built Stratoscope 2 finished 
making the improvements by September 1967. Then we 
put the entire telescope into a large test chamber where the 
air pressure and temperature were the same as they are 
at 80,000 feet. 

This time we put Stratoscope 2 through practice flights 
in the chamber. We found several weak parts during the 
first practice flights, and changed the equipment to cor- 
rect them. There were no failures during the last practice 




NATURE A \ I) SCIENCE 



flight, and we felt sure that we had made Stratoscope 2 
much more reliable than before. 

In February 1968 the telescope was tested on real stars. 
All of the mirrors and lenses in the telescope were care- 
fully adjusted. 

. . . And Again 

Tuesday, May 14, we were ready to launch, but it was 
raining. We had to wait. Saturday morning was perfect, 
so we inflated and launched the balloon without any 
trouble. After it had reached 84,000 feet, we started 
operating the telescope. We held our breath when the radio 
signal was sent to unlatch the telescope tube. It worked! 
Then we signaled the telescope to turn toward a star on 
which we wanted it to focus. 

We focused the telescope by moving one of its mirrors 
until the image of the focus star became sharp. But the 
image was not as sharp as we had expected. Could there 
still be blurring in the atmosphere above 84,000 feet? 
We did not think so. Instead, we decided that something 
in the telescope was much hotter or colder than it should 
be. We suspected it was the main telescope tube. 

After we focused the telescope, we photographed a 
galaxy— a collection of stars, gases, and dust— and some 
nebulae— "clouds" of gas and dust. We took 160 photo- 
graphs, hoping that a few of them would be sharp. 

After Stratoscope 2 returned to earth, we developed 
the film. The pictures were more blurred than we had 
expected, and most of them were useless. Still, some of 
the photographs were the sharpest ones that had ever been 
made of the galaxy. 

We now know why the pictures were blurred. The 
lower part of the telescope tube was about 50 degrees 
warmer than the upper part. We had tried hard to make 
sure that the entire telescope would be at nearly the same 




Dr. Robert Danielson, shown (right) at the ground 
control station during a Stratoscope 2 flight, has 
been interested in astronomy since he was a boy. He 
built three small telescopes while he was in high 
school. In 1958 he was doing graduate work at the 
University of Minnesota, in Minneapolis, when he 
found out that Dr. Martin Schwarzschild (left) was 
working on the Stratoscope program there. Dr. Dan- 
ielson talked to Dr. Schwarzschild about the strato- 
scopes and joined the program that same year. Both 
are now professors at Princeton University, in 
Princeton, N.J. 



temperature. But we had not realized that the temperature 
would be so different in different parts of the telescope tube. 

What Now? 

We hope to launch Stratoscope 2 several more times. 
But we are already designing telescopes that will be 
launched into orbit aboard large satellites or space stations 
in the 1970s. These telescopes will be completely free of 
the earth's atmosphere and should take even sharper 
pictures than our stratoscopes could. Many of the designs 
for the satellite telescopes are based on the design of 
Stratoscope 2. 

Some of the satellite telescopes will probably fail and 
some will succeed— just as our stratoscopes did. But what 
we have learned about building, testing, and operating 
balloon-borne telescopes should give the satellite tele- 
scopes a greater chance for success ■ 



TELESCOPES IN SPACE 



The Orbiting Astronomical Observatory (OAO) shown 
on the cover of this issue carried 11 small telescopes 
into space last December. The telescopes are being 
aimed at young, hot stars, some of which are still being 
formed. These stars give off ultraviolet light, much of 
which is blocked from earthbound telescopes by the 
earth's atmosphere. By measuring the ultraviolet light 
given off by these young stars, astronomers hope to get 
clues to how the universe was formed. 

Two more OAOs are scheduled to be orbited on similar 
missions— the third one carrying a telescope with a 32- 
inch reflecting mirror (see "Big Eyes on Space, " page 8). 



Larger telescopes that are designed, like Stratoscope 2, 
to take sharp, clear photographs of objects in space may 
be sent into orbit in the 1970s, if funds are available. 
Space telescopes will probably never replace tele- 
scopes at the earth's surface for continuous study of 
the stars. In fact, new ground-based observatories are 
being built now and more are planned for the future. 
Several of these telescopes will be in the southern hem- 
isphere. The skies are usually clearer there than in the 
northern hemisphere, and the stars in the southern 
sky have not yet been studied very much through large 
telescopes. 



February 3, 1969 



13 




Eiwii 




Chocolate-brown oil. Foamy detergents. Living tnings. 
What happens when you mix these ingredients? 



■ On March 24, 1967, beachcombers in southwest Eng- 
land cried, "We've found oil!" But their cry was one of 
dismay. This was oil from the Torrey Canyon, one of the 
largest ships in the world. It had been carrying 1 1 7,000 
tons of oil when it struck a rocky reef a week earlier. 

Resort-owners, fishermen, and many other people were 
afraid of the oil. They knew what damage it could do, for 
man has spilled oil in the oceans before. The ships that 
carry oil sometimes leak it into the sea, and illegally wash 
their empty oil tanks at sea. Oil tanker accidents dump 
even larger amounts. The oil from the wreck of one tanker 
wiped out the entire oyster population of Narragansett Bay 
in Rhode Island. Oil pollution has killed many sea birds 
near the harbors of New York City. 

When oil from the Torrey Canyon reached land, gov- 
ernment officials decided that detergents would be the 
quickest cure. These chemicals help oil and water to mix. 
The officials hoped that detergents would make it easier 
for the waves to wash away the oil. So planes swooped 
down to spray the beaches with detergents. Housewives 
used their kitchen soaps, and children poured detergents 

14 



from beach pails. But now, it looks as if the "cure" was 
worse than the pollution itself. 

A New Carpet 

Luckily, biologists at Durham University in England 
had been studying life along the southwest coast less than 
a year before the wreck of the Torrey Canyon. Seven 
months after the wreck, the biologists made new studies 




so that they could compare the ocean life before and after 
the wreck. 

Many of their studies were made on rocks that are cov- 
ered by water at high tide and uncovered at low tide. The 
biologists found one dramatic change on the rocks. Those 
rocks that had been treated with detergents were covered 
with masses of green algae, tiny water plants. Before the 
pollution, they had not had this green "carpet." Neither 
did the rocks where the oil had not been treated with 
detergents (see Photos 2 and 3). 

The green algae grew quickly on the detergent-treated 
rocks because the animals that usually eat the algae had 
been killed by the detergent. The limpet is the main algae- 
eater on rocks along the English coast. It is a small, slow- 
moving animal covered with a cone-shaped shell (see 
Photo 2). And, sure enough, the biologists found no adult 
limpets on the detergent-sprayed rocks that they studied. 
But many limpets survived on the rocks that had been pol- 
luted by the oil alone. 

Get Whiter Plankton? 

The detergents seemed to have killed the limpets. But 
their effects might be even more disastrous. Biologists 
working at the Marine Biological Laboratory in Plymouth, 
England, discovered that only one part of detergent in a 
million parts of sea water can kill some kinds of plankton 
—the tiny living things that drift in water. 

Many plankton are so small that they can only be seen 
with a microscope, but their importance is great. They are 
the main food of many kinds of whales. More important, 
they are also eaten by small fish and many other animals. 
Then larger fish eat the plankton-eaters, and still larger 
animals eat the large fish (see diagram). Because the sur- 
vival of one group depends on others, death of the plank- 
ton in the sea may mean death for many other kinds of 
living things. 

How harmful the detergents have been to life along the 
English coast may not be known for several years. Mean- 
while, half a million tons of oil are spilled in the seas each 



year. A safe way for cleaning up this oil is needed. 

One possible treatment is now being investigated by 
scientists at Cardiff University, in England. They have 
mixed certain chemicals with ashes. The mixture makes 
oil droplets clump together. If certain oil-destroying bac- 
teria can be mixed with the chemicals and ashes and 
dumped on an oil spill, it might be possible to get rid of 
the oil quickly. This could be a cure for oil pollution, and 
one that isn't a threat to life in the oceans ■ 




The tiny plants and animals called plankton are eaten by 
larger animals, which in turn are eaten by still larger animals. 
The plankton are like the base of a pyramid; without them, 
all of the animals above the base could not live. 



tish sailors sprayed detergents on 
ches (1) in order to get rid of the 

On rocks that were not sprayed 
i detergents (2), animals such as 
pets (the large-shelled animals in 

photo) were not killed. On rocks 
iayed with detergents (3), the lim- 
js were killed and the rocks were 
iered with thick growths of algae 
■I; light-colored areas in the photo). 




KKAIN- 





Mystery Photo 



SOIL 



SAND 



WATER 



EMPTY 




What causes white lines like this to form near 
melting piles of snow along the road? 



r 

What will happen if? 

Put an ice cube into a small 
strainer and hang it over a 
pan on the floor. As the ice 
cube begins to melt, count 
how many drops of water drip 
into the pan in, say, one min- 
ute. When the ice cube is al- 
most all melted, will the water 
be dripping slower, faster, or 
the same number of times 
each minute as when the cube 
began to melt? 



V. 



STICK TAPED TO INSIDE 

Just for fun 

Make some jars that roll in 
funny ways (see diagrams). 
Paint them black so no one 
can see what is inside. Roll 
the jars across the floor and 
see whether anyone can guess 
what is inside each one. 





Can you do it? 

Fill a soda bottle 
with water and put 
a straw into it. 
Then take some 
clay and pack it 
i nto the bottle 
opening around 
the straw. Now can 
you drink any 
water through the 
straw? 



Submitted by Mary 
Krebsbach, Lake Crystal, 
Minnesota 



Fun with numbers and shapes 

The four lines drawn divide the 
circle into 9 parts. Can you divide a 
circle into 11 parts with 4 straight 
lines? Into 16 parts with 5 straight 
lines? 



For science experts only 

Why does a chunk of ice slowly lose 
weight even when it is kept at a 
temperature below freezing? 



ANSWERS TO BRAIN'BOOSTERS IN THE LAST ISSUE 

Mystery Photo: When water is under 
solved in it. When the w 

soda pop fizzes when you open thi 

What will happen if? Even though the 

inside it won't he - turned U| >wn, it will 

turn right-side-up immediately 

Can you do it? To break a i held hctween three lingers, slap j 

down on a desk or table. 

Fun with numbers and shapi hy a pebble caught 

in a bike tire. 

For science experts only: The girl was born in the southern hemisphere in 
ber, January, or K 'hern hem 

months. She now lives in the northern hemi 
February are winter months 



-, 



Using This Issue . . . 

\ (continued from page 2T) 



as the rest of the spoon? Can anyone 

! explain what the lens does to the light 
from the spoon? (The magnifying lens 
does not change the amount of light 
that is reflected from the spoon to 
your eye. It just spreads the light rays 

, farther apart, so they form a bigger 
image inside your eye. But the larger 
the image, the less light there is at each 
point of it. So the more you "magnify" 

I an object, the dimmer it appears. An 
object appears brighter through a tele- 
scope because the lens of a telescope is 
larger than the lens of your eye, so it 

: lets in a greater amount of light.) 
Your pupils can use their own eyes 
to test the benefits of larger objective 
lenses or mirrors in telescopes. While 

i they are looking at any object, have 
them very slowly close and then open 
their eyelids, letting less and then more 
light through the lenses of their eyes. 
They will see that the less light their 
eyes receive from an object, the dim- 
mer and the more "fuzzy" it appears. 
As their eyelids gradually let in more 
light from the object, its increasing 
brightness and clarity may make it ap- 
pear closer— as if they were seeing it 
through a telescope. 

Brain-Boosters 

Mystery Photo. Snow piles along 
the road often contain the remains of 
salt that was used to melt ice on the 
road. (Salt lowers the melting point 
of ice, allowing it to melt at tempera- 
tures below normal freezing.) As the 
snow melts, salty meltwater flows away 
from the snow. When the water evapo- 
rates, the salt is left behind in a white 
line. 

You can demonstrate this for your 
class by putting a little mound of snow 
or crushed ice mixed with salt on a 
piece of glass or plastic indoors. A 
white salt deposit will be visible after 
the meltwater evaporates. If you place 
some of the salty meltwater under a 
microscope, your pupils will be able 
to watch the salt crystals forming. 

What will happen if? As an ice cube 
melts and gets smaller, a smaller sur- 
face area is exposed to the air, so the 
ice cube melts more and more slowly. 
This can be demonstrated while the 
class is engaged in some other activity, 

February 3, 1969 



since it will take some time for the ice 
cube to melt completely. Every five 
minutes, have a pupil count how many 
drops of water fall from the ice cube 
in one minute. The numbers can be 
entered on a chart, and then one of 
the pupils can draw a line graph to 
show the decreasing "drip rate." 

Can you do it? If no air can get past 
the clay plug in the neck of the bottle, 
it will be impossible to suck much 
water through the straw. Any small 
amount of water that could be sucked 
out of the bottle would leave that much 
more room for the air in the bottle, 
allowing the air to expand, and de- 
creasing its pressure. The low air pres- 
sure in the bottle would then be 
insufficient to push out any more 
water. (For more information on air 
pressure and its effects on liquids, see 
"Discovering an 'Ocean' from the Bot- 
tom," N&S, Nov. 11, 1968.) 

Ask your pupils why their mothers 
probably make two holes in the top of 
a juice can before emptying the can. 
What happens if you make only one 
hole in the can? 

Fun with numbers and shapes. Here 
is how to divide a circle into 1 1 parts 
with 4 lines, and 16 parts with 5 lines: 





After the class has puzzled over 
these problems, you might put the fol- 
lowing table on the board: 
number of lines 12 3 4 5 6 
parts into which 2 4 7 11 16 ? 
circle can be divided 
increase in number 2 3 4 5 ? 
of parts 

The class should be able to see that 
if the progression continues, they 
should be able to divide a circle into 
22 parts with 6 straight lines. Can they 
doit? 

For science experts only. Most sol- 
ids melt into a liquid before evaporat- 
ing into a gas. A few substances, 
however, can bypass the liquid stage, 
changing directly from solid to gas 
through a process known as sublima- 
tion. Moth balls and iodine crystals 
can do this, and so can ice that is kept 



from melting by freezing temperatures. 

Ask your pupils whether they have 
ever noticed vapor rising from an ice 
cream vendor's open truck during the 
summer. The "dry ice" (frozen carbon 
dioxide) that is used to keep the ice 
cream cold sublimes into carbon diox- 
ide gas, without producing a liquid 
that would get the ice cream wet. 

Just for fun. After your pupils have 
tried filling jars with the materials sug- 
gested and seeing how this affects the 
ways the jars roll, you might ask them 
to bring in some "mystery jars" con- 
taining other substances or objects. 
The children can have some fun roll- 
ing each other's black-painted jars and 
trying to guess what is inside each one. 

N&S REVIEWS... 

(continued from page 1 T) 

sonable book. Mr. Soule presents this 
controversial topic with the skill of a 
true reporter. Where a sighting of an Un - 
identified Flying Object generates excite- 
ment, he generates excitement. Where 
cold and logical techniques of investiga- 
tion change a UFO into an Identified 
Flying Object, he presents cold facts. 
Where mystery remains, he leaves mys- 
tery. Far from taking sides in this con- 
troversy, Mr. Soule carefully outlines 
steps that have been successful in solv- 
ing some of the UFO puzzles, and with 
equal care he points out cases where 
investigations have failed and the UFOs 
remain unidentified. The reader is drawn 
into each case, and as a result, he is likely 
to enjoy the experience. 

Mars, Planet for Conquest, by Eric 
Bergaust (G. P. Putnam's Sons, 96 pp., 
$3.29), is for your older and space-con- 
scious pupils. The general reader would 
not find it suitable, for its facts are quite 
abruptly presented; its terminology is 
often far beyond its brief glossary; and 
its illustrations are only remotely related 
to the text. There is also vagueness here, 
much of it forced by our vague national 
program for planetary exploration. 
Nevertheless, scientifically oriented 
pupils should be able to gain much from 
this book, particularly about the tech- 
niques for searching for life beyond the 
earth and about propulsion systems for 
manned vehicles being designed to reach 
other planets. 

On Course! Navigating in Sea, Air, 

and Space, by S. Carl Hirsch (The Viking 

Press, Inc., 157 pp., $4.13), really should 

(Continued on page 4T) 

3T 



N&S REVIEWS... 

(continued from page 3T) 



become part of your library. A combina- 
tion of careful scholarship and good 
writing, plus interesting illustrations by 
William Steinel, make this book, a de- 
light for both pupil and teacher. From 
the voyages of the ancient Pytheas to 
those of the men of Project Apollo, the 
story of navigation is cleverly presented. 
Mr. Hirsch has brought to life cabin 
boys speeding up time; a prince whose 
quarterdeck was a rock; the incredible 
Columbus with his letter of introduction 
to the Great Khan of China; the non- 
sailors like Mercator, the chart-maker, 
and Harrison, the clock-maker. From 
the angles of Bowditch to the inertial 
guidance of the submarine Nautilus, the 
story of navigation is there, fascinatingly 
presented. 

Baseball-istics, by Robert Froman (G. 
P. Putnam's Sons, 128 pp., $3.49). Here 
is physics in a setting: the year 2000, 
when the Senators and the Mets finally 
reach the World Series. The mechanics 
of baseball are cleverly explained in an 
account of the big game: the reality and 
illusion of how a pitch curves, speed 
vs. velocity, pitching and gravity, mo- 
mentum and its exchange in the home 
run, acceleration distribution during a 
triple play, the knuckle ball, spikes and 
friction. Entertaining and informative, 
though for a true baseball fan, the end- 
ing gets a little out of hand. 

Take a Balloon, by A. Harris Stone 
and Bertram M. Siegel (Prentice-Hall, 
Inc., 62 pp., $3.95), poses questions in- 
volving simple principles of mechanics, 
electrostatics, sound, optics, and heat; 
shows how to investigate these questions 
with the aid of balloons; and then poses 
more questions for further investigation. 
Inquiry and self-learning are stressed. It 
is well done. 



Secret Codes and Ciphers, by Bernice 
Kohn (Prentice-Hall, 72 pp., $3.95). 
Children from 8 to 12 will find challenge 
and intrigue in this fascinating book 
about the art of "secret writing." The 
book covers the difference between codes 
and ciphers, different types of ciphers, 
some of history's most famous codes, 
and the art of the cryptanalyst. It shows 
children how to solve some simple 
ciphers and make up their own codes 
and ciphers. Illustrations by Frank Aloisc 
and large print add to the book's appeal. 
Much rainy-day fun here. — M.E.B. 



invesuR^' 



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ANIMALS THROUGH THE 
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plus special articles on early man, 
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INVESTIGATIONS IN MATTER 
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4T 



nature and science 

TEACHER'S EDITION 

VOL. 6 NO. 11 / FEBRUARY 17, 1969 / SECTION 1 OF TWO SECTIONS 

COPYRIGHT © 1969 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 



USING THIS ISSUE OF NATURE AND SCIENCE 
IN YOUR CLASSROOM 



nature 
and science 



Pacific Isle 

Islands hold a special fascination 
for man, and biologists have learned 
a great deal about life in general by 
studying the special conditions on 
islands. Charles Darwin's observations 
of life on the Galapagos Islands, off 
the western coast of South America, 
were vital in the formation of his 
theory of natural selection. 

The water that surrounds an island 
acts as a barrier to life that might 
reach it. The more isolated an island, 
the less chance that it will have a 
variety of life. Even when a seed or 
spore from a plant is carried thousands 
of miles on the wind, it may not survive 
when it lands on an island. The en- 
vironment there will be suitable only 
for certain kinds of plants; also, a new- 
comer may not be able to compete with 
(established plant life. 

Birds reach islands much more eas- 
ily than most other kinds of animals, 
and oceanic islands such as Kure often 
have great numbers of birds living on 
them. There would be far fewer birds 
living there, however, if they had to 
depend on the island for all of their 
needs. But the sea provides the food; 
Kure is used for resting and nesting. 

Topics for Class Discussion 

• How has man affected the distri- 
bution of life in the world? He has cir- 
cumvented all the major barriers, car- 
rying a variety of life— from viruses 
!to rats— with him. Scientists are trying 
to sterilize space probes to the moon 
and Mars so that we can learn some- 
thing about their environments before 



they are contaminated by life from the 
earth. 

The author mentions how a rat, per- 
haps introduced by man, is affecting 
the bird life of the island. You might 
discuss with your pupils the "good" 
and "bad" effects of other organisms 
which man has introduced into new 
environments (see "The Animal 
Movers," N&S, Oct. 2, 1967). 

• Why can only a limited number of 
species of birds live on Kure? What 
an organism does in a community is 
called its niche. This may include its 
nesting place, food, feeding method, 
and feeding time and place. No two 
species can occupy the exact same 
niche; eventually one species will not 
survive the competition. If Kure were 
larger, with a greater variety of terrain 
and plant life, it would provide more 
niches for birds (and other animals) to 
exploit. 

For Your Reading 

• Island Life, by Sherwin Carlquist, 
Natural History Press, Garden City, 
New York, 1965, $9.95. 

• The Alien Animals, by George 
Laycock, Natural History Press, Gar- 
den City, New York, 1966, $4.95. 

• Surtsey: The New Island in the 
North Atlantic, by S. Thorarinsson, 
Viking Press, New York, 1967, $6. 

A Look at Lenses 

Investigating lenses is fun, and 

much easier than your pupils might 

think on first glance at this Science 

(Continued on page 2T) 




IN THIS ISSUE 



(For classroom use of articles pre- 
ceded by •, see pages 1T-4T.) 

• Life on a Pacific Isle 

A biologist explores a tiny island to 
find out how so many species of ani- 
mals are able to survive there. 

• Brain-Boosters 

Spring Is on the Way 

The earliest signs of spring are 
changes in the growth of certain 
plants and the activities of certain 
animals. Your pupils can start look- 
ing for these signs right now. 

Soap Bubbles 

Your pupils can experiment with 
conventional bubbles and soap films 
of many exotic shapes. 

Mystery Object Contest Winners 

Can your pupils guess what these 
mystery objects are? 

• A Look at Lenses 

With a reading glass, or other type 
of magnifying lens, and a flashlight 
your pupils can investigate how real 
and virtual images are formed. With 
two lenses, they can make a simple 
telescope and a microscope. 



IN THE NEXT ISSUE 

What we know about the birth and 
death of stars, an article and Wall 
Chart by Roy A. Gallant. . . Study- 
ing the birds of Kure Island ... A 
Science Workshop investigation of 
memory . . . The mystery of the com- 
mon cold. 



February 17,1969 



Using This Issue . . . 

(continued from page IT) 

Workshop article. Besides finding out 
how to make a simple telescope and 
microscope, they can use their findings 
to formulate some general rules about 
how convex lenses form images. 

Suggestions for Classroom Use 

Most of your pupils probably have 
access to a "reading glass" or some 
other type of magnifying lens; even a 
plastic one will do. 

• To stimulate interest, have your 
pupils describe what they see as they 
( 1 ) move the lens from eye to arm's 
length while looking through it at an 
object across the room; (2) with eye 
to lens and lens against a printed page, 
slowly raise head and lens together 
from the page; (3) with eye at differ- 
ent distances from the page, move the 
lens back and forth from page to eye. 
The objects they observe through the 
lens will appear sometimes blurry, 
sometimes sharp; sometimes rightside 
up, sometimes upside down; sometimes 
reduced, sometimes enlarged in size; 
sometimes they disappear altogether. 

• To emphasize the refraction of 
light beams moving from water into 
air (Diagram 1 , page 14), place one 
end of a ruler on the penny in the 
water and move the ruler so that it 
"crosses the border" (surface of the 
water) at different angles. Your pupils 
can see that the part of the ruler in 
the water appears bent. 

• To help your pupils visualize how 
a light beam is refracted, get an axle 



NATURE AND SCIENCE is published for The American 
Museum of Natural History by The Natural History 
Press, a division of Doubleday & Company, Inc., fort- 
nightly September, October, December through March; 
monthly November, April, May, July (special issue). 
Second Class postage paid at Garden City, N.Y. and at 
additional office. Copyright © 1969 The American 
Museum of Natural History. All Rights Reserved. Printed 
in U.S.A. Editorial Office: The American Museum of 
Natural History, Central Park West at 79th Street, 
New York, N.Y. 10024. 



SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester 
per pupil, $1.95 per school year (16 issues) in quanti- 
ties of 10 or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's 
edition $5.50 per school year. Single subscription per 
calendar year (17 issues) $3.75, two years $6. Single 
copy 30 cents. In CANADA $1.25 per semester per 
pupil, $2.15 per school year in quantities of 10 or more 
subscriptions to the same address. Teacher's Edition 
$6.30 per school year. Single subscriptions per cal- 
endar year $4.25, two years $7. ADDRESS SUBSCRIP- 
TION correspondence to: NATURE AND SCIENCE, The 
Natural History Press, Garden City, N.Y. 11530. Send 
notice of undelivered copies on Form 3579 to: NATURE 
AND SCIENCE. The Natural History Press, Garden City, 
N.Y. 11530. 



with two wheels from a toy car or 
train, or you can make one with a 
dowel and two "wheels" from a Tinker 
Toy set. Place a strip of desk blotnng 
paper on a smooth tabletop and roll 
the axle across the blotter as shown 

smooth tabletop 



/ 


1 


1 

1 


/ / 1 


A 


// 

/ 

/ 


h\\ 


A 


u 


<4 


f ,' blotting // 
,' paper // 


f \ / ¥ 



wheels and axle 

here. When one wheel (side of light 
beam) moves from the tabletop (air) 
onto the blotter (water or glass) and 
slows down before the other wheel 
slows down, the axle tends to change 
direction. Also roll the axle from the 
blotter to the tabletop at different 
angles. 

• To see how parallel beams are 
focused by a convex lens (Diagram 3), 
chalk dust slapped from an eraser is 
handy for making beams visible in the 
dark. Have your pupils punch four 
more holes in the foil, forming a circle 
around the center hole. They can see 
all these parallel beams form a cone 
between the lens and its focal point, 
showing that beams do not have to be 
in a single plane (or "lined up") to 
be brought to a focus. Have your pu- 
pils tip the lens so it is not parallel with 
the flashlight face and see what hap- 
pens. (The focal point moves, but its 
distance from the center of the lens 
remains the same.) 

• Finding the focal distance of a 
lens by focusing beams of light from 
a distant object on a screen is fun 
and easy to do (see Diagram 4). Some 
of your pupils may know that beams 
of sunlight focused in this way can 
produce enough heat at the focal point 
to burn a hole in the "screen." 

Your pupils will notice that the 
image of a distant object formed by 
the lens is upside down and much 
smaller than the object itself. Can any- 
one guess what common tool uses this 
particular image-forming ability of a 
lens? (A camera lens forms an upside- 
down image on the film to record a 



picture of a scene or object.) 

• Have your pupils project an 
image from a flashlight face as shown 
in Diagram 5, then try to complete the 
paths of Beams C and D in Diagram 6. 
(C passes through the focal point on 
its way to the lens, so it leaves parallel 
to the lens's principal axis. D travels to 
the lens parallel to that axis, so it passes 
through F on the other side of the 
lens.) 

Explain to your pupils that for dia- 
graming purposes, a thin lens can be 
treated as if all the refraction takes 
place halfway through the lens (at its 
vertical axis), as shown in Diagram 6 
and on page 16. The true refraction 
can then be shown by a line connecting 
the points where the beam enters and 
leaves the lens. 

• Have your pupils see what hap- 
pens to the image when the object is 
placed at other distances from the lens, 
as suggested in the article, then try to 
diagram the paths of light beams from 
the top and bottom of the object in 
each case (as shown below). By re- 
peating these tests with lenses of dif- 
ferent focal lengths, they should be 



object 






image 


l^-^F^^L 


L^T^-^l 


2F 






2F 



ftg ffix^n 



2F 



able to summarize their findings in 
some general rules about convex 
lenses, in substance: 

If two convex lenses have about the 
same diameter, the "fatter" lens has 
the shorter focal distance. For each 
particular distance of the object from 
the lens (down to the focal distance or 
closer) a sharp, upside-down image of 
the object will form on a screen at a 
(Continued on page 3T) 



2T 



NATURE AND SC1ENCB 



VOL. 6 NO. 11 / FEBRUARY 17, 1969 



nature 

and science 



You can make a simple 
projector, a telescope, 
and a microscope with 
two magnifying lenses. 

see page 14 

A LOOK AT LENSES 





VOL. 6 NO. 11 / FEBRUARY 17, 1969 
CONTENTS 

2 Life on a Pacific Isle, Part I, 

by Alan H. Anderson, Jr. 

6 Brain-Boosters, by David Webster 

7 What's New?, by B. J. Menges 

8 Spring Is on the Way, by Laurence Pringle 
10 Soap Bubbles, by Madison E. Judson 

1 2 Mystery Object Contest Winners 

24 A Look at Lenses, by Franklyn K. Lauden 



PICTURE CREDITS: Cover, Fundamental Photographs; pp. 2-3, William 
Wirtz; p. 4, top, Allen D. Cruickshank, middle, O. S. Pettingill, bottom, T. M. 
Bailey, all from National Audubon Society; p. 5, top, T. M. Blackman, from 
National Audubon Society, middle and bottom. Alan H. Anderson, Jr.; pp. 6-12. 
14-16, drawings by Graphic Arts Department, The American Museum of 
Natural History; p. 6, photo by Dave Webster; pp. 7, 8 (top), 9, photos by 
Leonard Lee Rue III; p. 8 (bottom), photo by R. D. Muir, from National 
Audubon Society; p. 10, Franklyn K. Lauden; p. 12, (1) Wendy Levoy, (2) 
Marcus Levitt, (3) Jim Donohue; p. 13, Victor Stokes; p. 15, photo by Roy A. 
Gallant from Science Photo/Graphics, Ltd. 



PUBLISHED FOR 

THE AMERICAN MUSEUM OF NATURAL HISTORY 

BY THE NATURAL HISTORY PRESS 

A DIVISION OF DOUBLEDAY & COMPANY, INC. 

editor-in-chief Franklyn K. Lauden; executive editor Laurence P. 
Pringle; associate editor R. J. Lefkowitz; assistant editors Mar- 
garet E. Bailey, Susan J. Wernert; editorial assistant Alison New- 
house; art director Joseph M. Sedacca; associate art director 
Donald B. Clausen • consulting editor Roy A. Gallant 

publisher James K. Page, Jr.; circulation director J. D. Broderick 
promotion director Elizabeth Connor 
subscription service Frank Burkholder 

NATIONAL BOARD OF EDITORS 

PAUL F. BRANDWEIN. CHAIRMAN, Dir. of Research, Center for Study of 
Instruction in the Sciences and Social Sciences, Harcourt, Brace & World, Inc. 
J. MYRON ATKIN, Co-Dir., Elementary-School Science Project, University of 
Illinois. THOMAS G. AYLESWORTH, Editor, Books for Young Readers, 
Doubleday & Company, Inc. DONALD BARR. Headmaster. The Dalton 
Schools, New York City. RAYMOND E. BARRETT, Dir. of Education, Oregon 
Museum of Science and Industry. MARY BLATT HARBECK. Science Teach- 
ing Center, University of Maryland. ELIZABETH HONE, Prof, of Education, 
San Fernando (Calif.) State College. GERARD PIEL, Publisher, Scientific 
American. SAMUEL SCHENBERG, Dir. of Science, New York City Board of 
Education. WILLIAM P. SCHREINER, Coord, of Science, Parma (Ohio) City 
Schools. VIRGINIA SORENSON, Elementary Science Consultant, Dallas In- 
dependent School System. DAVID WEBSTER, Staff Teacher, Elementary 
Science Study, Education Development Center, Newton, Mass. • REPRE- 
SENTING THE AMERICAN MUSEUM OF NATURAL HISTORY: FRANK- 
LYN M. BRANLEY, Chmn., The American Museum-Hayden Planetarium. 
RICHARD S. CASEBEER, Chmn.. Dept. of Education. THOMAS D. NICH- 
OLSON, Deputy Dir., AMNH. GORDON R. REEKIE, Chmn., Dept. of Exhibi- 
tion and Graphic Arts. DONN E. ROSEN, Chmn., Dept. of Ichthyology. 
HARRY L. SHAPIRO, Curator of Physical Anthropology. 

NATURE AND SCIENCE is published for The American Museum of Natural History by 
The Natural History Press, a division of Doubleday & Company, Inc., fortnightly 
September, October, December through March, monthly November, April, May, July 
(special issue). Second Class postage paid at Garden City, NY. and at additional 
office. Copyright © 1969 The American Museum of Natural History. All Rights Re- 
served. Printed in U.S.A. Editorial Office: The American Museum of Natural History, 
Central Park West at 79th Street, New York, N.Y. 10024. 

SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester per pupil, $1.95 per school 
year (16 issues) in quantities of 10 or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's edition $5.50 per school year. 
Single subscription per calendar year (17 issues) $3.75, two years $6. Single copy 30 
cents. In CANADA $1.25 per semester per pupil, $2.15 per school year in quantities 
of 10 or more subscriptions to the same address. Teacher's Edition $6.30 per school 
year. Single subscriptions per calendar year $4.25, two years $7. ADDRESS SUB- 
SCRIPTION correspondence to: NATURE AND SCIENCE, The Natural History Press, 
Garden City, N.Y. 11530. Send notice of undelivered copies on Form 3579 to: 
NATURE AND SCIENCE, The Natural History Press, Garden City, N.Y. 11530. 






PART 1 



aT=X=TlXi iu¥» 



land iooke< 
nd lifeless. Then I land 
and discovered a fascinatin< 
community of plants and anii 
living there. 




■ When I first saw Kure Island, a tiny dot in the Pac 
1,200 miles northwest of Honolulu, I wondered wh 
biologist would want to study it. A mile-and-a-half sli 
of beach and shrubs (see photo), it just barely deservec 
be called an island. What could live there. 1 wondered 

The cold February fog was so thick that our twin-eng 
plane had to return 50 miles to Midway Island for anot 
try later. And for the moment I was glad. 

But the next afternoon the sun broke through. The p 
gave me a tour of the gleaming blue-green lagoon, dip} 
the plane so low over the reef that the wing nearly skimn 
the white-topped waves. As we touched down on the co 
sand runway, scores of white-winged albatross ran clum! 
to get up speed, then caught the wind and soared gra 
fully out to sea. I forgot the fog and gloom of the <. 
before. 

Kure was to be my home for the next two-and-a-h 
months. I learned before I left: No matter how simp! 
looks from the air, any island big enough to land an ; 
plane on is sure to have puzzling questions for a biofp 

NAT! A'/ l\/> s< ienci 






ON A PACIFIC ISLE 



by Alan H. Anderson, Jr. 




Kure Island is part of the rim of an ancient volcano's crater. The white line 
of breaking waves marks the rest of the crater's rim. Dark-colored Scaevola 
bushes cover most of the island. 



to investigate. 

All About an Atoll 

A biologist who wants to study the life of an island (or 
,other area) is called an ecologist. Ecology is the study of 
how living things depend on other living things and on 
other parts of their living area, or environment. This means 
i the ecologist has to be aware of everything: birds, insects, 
,i mammals, plants, soils, weather. And this is why ecology 
is complicated, even on a small island like Kure. 

One ecologist said recently that he knew of no island, 
l no matter how small, on which all forms of life were posi- 
tively known. Something new is always popping up, he 
.said, or something that used to be there is disappearing. 

Kure is an atoll— the top of a volcano that long ago 
erupted from the bottom of the sea. Kure used to be quite 
'a bit larger— about 15 miles across— but, like the other 
western Hawaiian islands, it has been slowly worn away 
by winds and waves. Now Kure is only one tiny bump in 
the rim of what used to be the crater of the volcano. 



As I stepped out of the plane, I met the other two men 
whom I would work with. They showed me the small Coast 
Guard station where we would live. Then we all set out 
for a walk around the island. 

I had already realized that Kure was a special place. 
Over two-thirds of the land was covered with dense Scae- 
vola bushes, whose thick green leaves and tough stems 
could withstand the punishment of winter storms and 
constant salty winds. This meant that all the animals that 
lived there had to "learn" to live with the Scaevola. Where. 
I wondered, could the 14 kinds (species) of birds that lived 
on Kure make their nests? 

I knew that no two species of animal can lead exactly 
the same way of life in exactly the same place. One would 
survive the competition; one would not. On Kure, for ex- 
ample, this meant that two species of birds eating the same 
food and behaving in the same way could not use the same 
nesting areas. 

Some 50 species of birds visit Kure, but I was most in- 

(Continued on the next page) 



February 17, 1969 





Frigate birds (above) 
scoop their food from 
the surface of the sea, 
or chase other birds un- 
til the birds drop food 
they carry. The Laysan 
albatross (left) also 
catches food from the 
surface of the sea. 




Life on a Pacific Isle (continued) 

terested in the 1 4 that nest there. They included the Laysan 
albatross and its slightly larger relative, the black-footed 
albatross, both of which have wingspreads of seven feet or 
more. There were three kinds of boobies, which are gull- 
to goose-sized birds with strong, jagged bills for grasping 
slippery fish. There were also smaller brown-and-white 
shearwaters and petrels; pure white tropicbirds with a one- 
or two-foot-long red tail feather trailing behind; frigate 
birds, strong, black pirates of the island that steal fish from 
the other birds; and chattering terns whose cries filled the 
night air over the island. 

Here were 14 species of birds, all getting their food from 
the sea and all nesting on a small area covered largely by 
one kind of plant. What differences could there possibly be 
in the way they lived? 

When an Albatross Throws Up 

We walked north from the Coast Guard station through 
the central plain, the only large open area of the island. 
Amid the clumps of grass, Laysan albatross and blue- 
faced boobies had made their simple nests, side by side. 

This seemed to break our "rule"— two species were liv- 
ing on the same island, nesting side by side, and perhaps 
eating the same food. 

But were they? Answering this question turned out to be 
simpler, though less pleasant, than I thought. I decided to 



try to catch my first albatross. I did this by approaching the 
bird from the direction of the wind. These birds are so big 
and heavy that they must take off into the wind, as an air- 
plane does. With no wind to help, they may run several 
hundred feet, flapping furiously, only to tumble in a grace- 
less heap in the sand. 

After a few misses, I caught a Laysan albatross by the 
neck just as it was about to rise into the air. No sooner had 
I gotten a firm grip with two hands than it "threw up" its 
lunch, and perhaps its breakfast— several pounds of purple 
squid and squid eggs. Most sea birds of this area do the 
same thing when they are handled. Perhaps they have 
learned that it is the only way to escape a pursuing frigate 
bird. This pirate will chase another bird until it empties its 
throat and stomach. Then the frigate bird dives after the 
falling food. 

In any case, I was partly repaid for the mess on my shoes 
by finding out what the albatross cats. The next step was to 
try the same method on the blue-faced booby. This time I 
held the bird's head at a good distance. It threw up a 
glistening, partly-digested fish about 10 inches long. 

The booby dives for its food, its body streamlined as an 
arrow, its bill tremendously strong and jagged. By contrast, 
the albatross does not dive. It catches squid and other food 
on the surface. So the two birds have quite different ways 
of life. 

As I was walking across the open area, one leg suddenly 
gave way and I fell headlong. I had accidentally discovered 
how another species of bird nests on Kure. The wedge- 
tailed shearwater digs a deep burrow for its nest by using 
its strong legs and sharp toes. In this way it docs not com- 
pete for nesting places with its upstairs neighbors, the 




Even with a wingspread of seven feet, the heavy-bodied black- 
footed albatross must run a long distance into the wind be- 
fore it is able to lift into the air. 



NATURE AND SCIENCE 



albatross and the booby. 

At the edge of the beach I saw a reason why the two al- 
batross , so much alike in looks and food habits, could 
share the same island. The blackfoots did not compete with 
the Laysans for nesting space in the open areas. Instead, 
they chose a more dangerous area, near the beach. I was 




By digging a nest burrow several feet underground, the 
wedge-tailed shearwater avoids competing with other birds 
for nesting space on the surface of the ground. 

told that they had paid for their choice earlier that winter 
when a storm destroyed a third of their nests. Some birds 
had been found dripping wet, trying— between waves— to 
sit on eggs which were afloat or rolling down the beach. 



living on less than a dozen atolls in the Pacific. Al Kurc. il 
sleeps on the beaches and gives birth there to jet-black, 
gruff-voiced pups in the spring. 

Crossing the lower half of the open area on the way back 
to the station, 1 noticed one effect of another animal on 
(Cure Island, the Polynesian rat. No one knows whether 
this small rat reached Kurc by stray dugout canoe or by 
shipwrecked sailing vessel, but thousands of them live amid 
the Scaevola bushes, eating seeds and buds. 

I found an adult Laysan albatross with a two-inch-wide 
wound in its back. The rats had discovered how to climb 
onto a sleeping bird without disturbing it and chew a hole 
through the feathers and skin of the back. The bird would 
die in a day or two from loss of blood or from infection. 
Then the rats would eat it completely. The rats were killing 
not only the adult and young albatross but also young 
tropicbirds. 

How long have the rats been doing this? What is likely 
to be the effect on the bird populations? These are ques- 
tions an ecologist can answer only after much more study ■ 

//; the next issue, the author describes some oj the things 
he learned about the animals during the 10 weeks he stayed 
on Kure Island. 



On his first hike around Kure Island, the author found a 
Hawaiian monk seal near the beach. He also discovered that 
the red-tailed tropicbird nests under the Scaevola bushes. 



Under and On Top of the Bushes 

Near the western beach we found both red-footed 
boobies and frigate birds making nests out of twigs and 
vines in the tops of the Scaevola bushes. This seemed odd, 
since the frigates often chased boobies returning to the 
island with fish. For a time, it seemed that these birds 
were competing with each other for both food and nesting 
sites. By applying the "throw-up test," it was easy to find 
out that they probably were not. We discovered that the 
boobies ate whole fish, while the frigates either scooped 
squid from the surface or pirated their meals from other 
birds. 

As we cut in from the beach toward the runway, a loud 
squawk came from hear my right foot. I looked down and 
saw a tropicbird with feathers bristling. It had found a way 
of life on the ground beneath the bushes (see photo). Here 
it did not compete for nesting space with any of the other 
birds. 

Past the next clump of high bushes I discovered a sleep- 
ing Hawaiian monk seal (see photo), about six feet long 
and probably weighing over 500 pounds. It awoke with a 
start and grunted loudly, then hunched and flopped past 
us onto the beach. It is one of the rare seals of the world, 

February 17, 1969 




JUST FOR FUN 

Here is how to make a hose tr ir 
bone: Make a bend as shown in 
garden hose that has some writ 
in it. By lifting the end of the ho 
up and down, you can make t 
water level rise and fall. This a 
change the length of the air colin 
inside the hose. If you blow aero 
the open end of the hose, you W 
hear a sound that is higher or low 
depending on the length of the z 
column. How does shortening t 
air column change the sound? 




FUN WITH 
NUMBERS 
AND SHAPES 



Here are five 5s arranged to equal 1. Can you ar- 
range five 5s to equal each of the numbers from 2 

through 12? Submitted by M. Bruce, Victoria, Canada 

FOR SCIENCE EXPERTS ONLY 

Why does the water in a toilet move up and down 
when the wind blows hard? 

WHAT WILL HAPPEN IF? 

Which thermometer will go up fastest when these jars 
are put in sunlight? Which will show the highest read- 
ing after three hours in the sunlight? 

WATER WITH FOOD 
EMPTY /} WATER /? WATER yO COLORING 



^ 




^^ 



HAVE YOU AN IDEA FOR A BRAIN-BOOSTER? 

Send it with the solution to David Webster, R.F.D. #2, 
Lincoln, Massachusetts. If we print it, we will pay you $5. 
Be sure to send your name and address. If several readers 
submit the same idea, the one that is most clearly pre- 
sented will be selected. We regret that ideas cannot be 
returned or acknowledged. 



ANSWERS TO BRAIN-BOOSTERS 
IN THE LAST ISSUE 



Mystery Photo: Snow piles along the road often contain the re- 
mains of salt that was used to melt ice. As the snow melts, salty 
meltwater flows away from the snow. When the water evaporates, 
the salt is left behind in a white line. 

What will happen if? As an ice cube melts, it drips slower and 
slower. This is because a small piece of ice has a smaller surface 
area exposed to the warm air than a larger piece of ice has. 

Can you do it? If no air can get into a soda bottle filled with 
water, you will be unable to suck out much water through a 
straw. What will happen if you blow into the straw? 



Fun with numbers and shapes: One circle 
has been divided into 1 1 parts with 4 lines. 
The other circle has been divided into 16 
parts with 5 lines. What is the greatest 
number of parts into which you can divide 
a circle with 6 straight lines? 



For science experts only: Some solids, such as ice, mothballs, 
and iodine crystals, can slowly change into a gas without first 
going through a liquid stage. Ice can change into water vapor 
even at freezing temperatures. 






WHAT'S 

B. J. Menges ^r 

Bloodsucking moths have been dis- 
covered in Thailand and Malaya. Most 
moths sip nectar, not blood. But a few 
years ago, a Swiss scientist found blood 
in the stomachs of certain moths. Other 
scientists joined the investigation, and 
Dr. H. Banziger of Zurich, Switzerland, 
was first to identify the moths that drink 
blood. 

There are two ways in which moths 
can drink blood. Some kinds (species) of 
bloodsucking moths sip blood from open 
wounds or from drops of blood left by 
mosquitoes. Other species of bloodsuck- 
ing moths pierce the skin of an animal, 
and then sip. In both cases, the moth 
drinks through its proboscis, a long, hol- 
low tube that rolls up in a coil under the 
moth's head when not in use. The pro- 
boscis of the skin-piercing moths has a 
hard, sharp end that can pierce the skin 
of a water buffalo, an antelope, or a man. 
This feels like being jabbed with a red- 
hot needle, according to a man who let 
himself be "bitten" for science. 

Sailing a tall ship under. a low 
bridge may be possible with a scheme 
dreamed up by two Soviet inventors. The 
scheme calls for a motor-driven barge as 
wide and long as a football field and as 
tall as a four-story building (see diagram). 
The hollow barge is filled with water un- 
til it floats three-quarters submerged, 
with the water level inside the same as 
that outside. 

A ship enters the barge through gates 



at the rear. Then the gates close, and 
some of the water inside is pumped out. 
It isn't pumped to the outside, though, 
since the barge would then be lighter 
and would float higher. Instead, the 
water is pumped into tanks between two 
outer walls of the barge. Since the total 
weight of the barge remains the same, 
the barge floats as before. But the water 
level inside the barge drops below the 
water level outside the barge. This lowers 
the ship enough so that the barge can 
carry it under the bridge. Once the ship 
is past the bridge, the water level inside 
the barge is raised, gates in the front are 
opened, and the ship sails on its way. 

Collisions with birds are a serious 
danger to airplanes in flight. For years, 
scientists have tried to eliminate this 
danger. Now a research team in Canada 
believes radar may be the answer. Radar 
signals are generally used to detect ob- 
jects that are in the dark, or that are too 
far away to be seen. But the signals have 
also been found to "sweep" birds out of 
their way, making them fly higher or 
lower. 

Radar beams sent forward from a fly- 
ing aircraft could thus clear birds from 
the path of the plane. The signals don't 
harm the birds; for some unknown rea- 
son they sjmply nudge them away. It is 
hoped that this method can eventually 
be used to save millions of dollars, as 
well as the lives of many humans and 
birds. 

Worrying about schoolwork 

could be bad for your teeth. So says Dr. 
Martin R. Protell, a dentist in New York 
City. For the past 10 years Dr. Protell 
has treated the teeth of people in a 
mental hospital, as well as those of the 
people who visit his office. From his ex- 
perience, he has concluded that tension 
and worry can cause tooth troubles. 

Dr. Protell believes that when tensions 
are "held inside" a person and not re- 
leased by shouting, fighting, or similar 
behavior, extra strain is put on the 




nervous system. This causes the blood to 
carry a less-than-normal load of various 
substances that promote health and fight 
disease. Some of the unfortunate results 
may be trenchmouth, bleeding gums, and 
tooth decay. 

Trumpeter swans have won their 
fight for survival. In 1935, only 73 of 
these big birds were left in the United 
States. Now there are over 4,000. The 
trumpeter, named for its powerful horn- 
like call, is the heaviest of all North 
American wild birds, sometimes weigh- 
ing over 30 pounds. The species was 
hunted for its meat, as well as for its dec- 
orative white feathers, until it was in 
danger of becoming extinct. 




The United States government then 
began a program to save the trumpeter. 
The birds and their breeding grounds 
were protected, some birds were moved 
to new areas, and young trumpeters were 
raised in zoos. Today, after over 30 
years of effort, the trumpeter is ap- 
parently safe. Conservationists hope that 
a similar protection plan can remove the 
whooping crane from the list of threat- 
ened species (see "Egg-Stealing Scien- 
tists," in "What's New?", N&S, October 
14, 1968). 

Caviar is hard to find in Russia 
these days. Caviar is the salted eggs of 
certain fishes. Black caviar, the eggs of 
sturgeon, is a favorite Russian delicacy, 
and one of the country's major exports. 
But sturgeon and their eggs are becoming 
scarce. One reason is that industries are 
polluting the Caspian Sea, where stur- 
geon live, and the Volga River, which 
flows into it. Also, many of the sturgeon's 
breeding grounds in the Volga have been 
destroyed by a steady drop in the water 
level. Too much river water is used for 
industry and irrigation. 

As a result, Russians must pay about 
$10 a pound for black caviar, or else 
settle for the less appetizing red caviar 
produced by salmon. And they have to 
import from Iran some of the black 
caviar they sell abroad. 



February 17,1969 



I 

February 17, 1969 



* ♦• 




,V ' ; *r I'M 



■ Spring begins officially about March 21, when the 
rays of the sun shine directly down on the equator 
and begin moving northward. But there's snow and 
cold in many parts of North America on March 21; 
"real" spring seems far away. 

Since December 21, however, the days have been 
getting longer. The lengthening days have triggered 
many changes in nature. Spring is an important time 
of growth and reproduction for plants and animals. 
Some of them have ways of behavior or other char- 
acteristics that enable them to begin their spring 
activities long before spring is officially here. 

Even now — in mid-February — you can find signs 
of spring outdoors. The photos and drawings on this 
Wall Chart show some examples to look for in your 
area. Can you find some others? — Laurence Pringle 



5TING IN THE SNOW, the great horned owl gets an early star 
on raising its young. Two or three eggs are usually laid in Febri 
ary, and the parent birds keep the eggs warm even when the ai 
temperature drops below zero. 







CUTAWAY VIEW 
OF ELM BUD 



to develop into flowers, leaves, and twigs 
of trees and shrubs. If you cut down through the center of 
a bud, you may find the young leaves (see diagram) 
that would have appeared in the spring. They are pro- 
tected from drying out by layers of tough bud scales. 
Even now you may be able to find buds that are swelling 
and changing color as growth begins inside. Cut twigs 
from different kinds of trees and shrubs, set them in water 
inside near a window, and watch to see what grows from 
the buds. 



• 







are a traditional sign of 
spring. In most of the northern United States, 
the robin is thought to be the "first bird of 
spring." But some robins spend the entire win- 
ter in the north, and other birds— such as these 
red-winged blackbirds— may actually arrive be- 
fore those robins that migrate. Start watching 
to find out which kind of bird is first to return 
from the south to your area. 



SNOW FLEA 



LONG 



I 



SNOW FLEAS hop like fleas but are really members of a 
group of insects called springtails. They are just one of sev- 
eral kinds of insects you may see on the snow, especially 
when the temperature is a little above freezing. Snow fleas 
swarm by the millions so that the snow is sometimes black- 
ened for yards around the place where they have come up 
through a crack in the snow. They feed on decaying plant 
material and apparently come to the surface of the snow 
when their food supply runs out. Another kind of insect, the 
snow fly, mates on the snow. Then the female digs down to 
the earth and lays her eggs. 



SNOW FLY 






(February 2) is 
supposedly the one winter day when 
groundhogs (woodchucks) come up 
from their underground burrows. Ac- 
cording to an old saying, "If the 
groundhog sees its shadow on Febru- 
ary 2, there will be six more weeks of 
winter weather." But woodchucks may 
be seen on many other winter days, 
and their appearance has nothing to 
do with the future weather. Ground- 
hogs spend most of the winter in a 
deep, death-like sleep called hiberna- 
tion. They sometimes wake from this 
sleep, however, and come to the sur- 
face, especially on warm winter days. 







Vs" - l A" LONG 



the skunk 

cabbage plant grows even when the air temper- 
ature is below freezing. Inside the brown and 
green shell-like structures called bracts (see 
photo) are the skunk cabbage flowers. As the 
flowers develop, they "burn" food energy that 
was stored in the plant's roots, and give off 
heat. The temperature of the flowers may reach 
120° Fahrenheit. Some of this heat is given 
off into the air and melts snow around the plant. 




Soapy water makes bigger and better bubbles than plain 
water because a soap bubble's "skin" is made of a thin layer 



of water sandwiched between two layers of soap. The soap 
layers help keep the water layer from evaporating. 



■ "What do you know about soap bubbles?", I asked a 
friend of mine in the fifth grade. "They pop!", she said, 
and that was that. What she meant was that bubbles usually 
break just when you want to look at them a little while 
longer. The amazing thing about bubbles, though, is not 
that they pop, but that they form at all. 

If you want to become a bubble observer, there is no 



need to go out and buy bubble mixes; you can make your 
own. Just mix two capfuls of dishwashing liquid with 
one cup of water. Then if you add one teaspoon of sugar, 
the bubbles you make will last longer than bubbles made 
with soapy water alone. 

You can use water from the tap, but rainwater is better, 
because it doesn't contain the chemicals that sometimes 







■ i < — 1 1 

— n 1 . — — . 

■ ■ 1 ■ — i 

1 1 1 , ,_ 

■ ■ — .1 . — ■ ■-< — — ■ i - i — 

— — — — — — — — ■ — — -i — 

. 1 1 — — ■ 1 ■ 1 — 

1 I 1 -' — . 

■ ■ " - — - ■ ■ ■ - .1 ' — I — 

I - ' - - ■■■ — ■ ■ ■ ■ ■ 1 — 



HALF-INCH SCREEN 




make tapwater "hard." When you mix the detergent and 
the water, make sure that the water is cold. Cold water 
will keep the suds down. 

The drawings on this page show several bubble-blowing 
tools that you can make or buy. You can even use an or- 
dinary drinking straw; if you do, split and fold the end 
back, as shown in the drawing. A kitchen funnel works 
well, too, but you will have to wet the inside of the funnel 
with the soap liquid before blowing through it. You can 
buy a plastic wand, or you can easily make one out of 
wire. Making bubbles with wire screening— half-inch screen 
is best— can also be fun. Try using large-hole screen, such 
as chicken wire, also. 

Whatever kind of bubble wand you use, dip the wand 
into the soap liquid, lift it out, then gently wave it through 
the air to form bubbles. To free a bubble from the wand, 
twist the wand gently when the bubble is just about formed. 
If you blow through the wand, blow gently; otherwise you 
will break the soap film. If you want to make large bubbles, 
dip the big end of the funnel into the bubble solution (after 
wetting the inside of the funnel), then blow gently through 
the small end. If you run out of breath before you finish 
making the bubble, stick your tongue over the opening 
while you take another breath. This will keep the bubble 
from collapsing. 

When the large end of the funnel is dipped in the soap 
liquid, a soap film will form across the mouth. Watch the 
soap film. It will travel up the funnel. Can you figure out 
why it does? 

Make a bubble holder (see diagram), so that you can 
study a bubble closely. After you make a large bubble with 
the funnel, see if you can put the bubble on the wet wire 
loop of the bubble holder. Then, using another wet wire 
loop, see if you can remove the bubble again. 



PROJECTS 



For Bubble Experts Only 

• Did you know that you can put your finger 
inside a bubble? First wet your finger with the 
soap liquid. Your finger will then pass easily 
through the wall of the bubble without breaking it. 

• Place a large bubble on a wet surface. Then wet 
a drinking straw in the bubble liquid and push the 
straw into the bubble. Now see if you can blow 
another bubble inside the first bubble. 

• Dip a soap film frame into the bubble liquid 
and put it into the freezer of your refrigerator. 
What happens? Can you find a way to freeze a 
soap bubble? Try using frames of different shapes. 
Can you freeze a bubble outside on a cold night? 



Experimenting with Soap Films 

A bubble is only one shape that a soap film may take. 
Many other shapes are easy to make by bending wire into 
frames of different shapes and stretching a soap film over 
them. Number 20 copper wire is easy to bend, but any kind 
of wire that stays in the shape you bend it will do. 

Make a long -loop bubble wand (see diagram). The loop 
should be about two or three inches across. After you have 
dipped the loop in the soap liquid, lift it out and hold the 
wand edge-up. Watch the soap film as it gradually develops 
bands of color. 

By making a soap film slider like the one shown in the 
diagram, you can have a tug-of-war with a soap film. When 
you remove the slider from the liquid, watch to see what 
happens. Pull the slider out and watch the soap film 
stretch. Release the slider and watch the film contract. 

(Continued on the next page) 




Soap Bubbles (continued) 

Make a thread loop inside a square wire frame. The 
thread should be light weight and made of silk or rayon. 
Dip the frame and loop in the bubble liquid, take it out, 
then touch a paper towel or tissue to the inside loop. Watch 
what the rest of the soap film does. 

Invent some wire-frame shapes of your own. Maybe 
the cube and prism shapes shown in the diagram will give 
you some ideas. The soap films form in surprising ways 
when you use frames like these. Try to make a soap film 
form on all six sides of the cube. Maybe it can't be done. 

Some unusual things happen when you use a spiral 
frame. Study the one in the diagram, see how the loops 
wind around, then make one like it. Make a "Moebius'* 
loop and find out what happens after you dip it into the 
liquid. 

You can watch a soap film for quite a long time if you 





TURN JAR .J^^fc 



use a bubble jar (see diagram). Your wire frames can be 
held firmly by the gasket, or cardboard, inside the cap. 
You can cut a good gasket from an old inner tube. As the 
diagram shows, make the hole in the gasket near one edge 
of the disc, riot at the center. By making the hole near the 
edge you will not need as much bubble liquid as you would 
if you made the hole in the center of the disc. When the 
bottle cap is tightened in place, turn the bottle on its side 
and roll it so the wire loop dips into and then out of the 
liquid. You can then stand the bottle upright to study the 
soap film. Make a four-sided frame also, and see what hap- 
pens to the soap films that form on it. 

The many projects in this article are only a few of the 
things you can do with bubbles and soap films. Once you 
start experimenting you will discover dozens of other things 
to do and to look for ■ 
12 





3 



ft! 



Do these pictures puzzle you s 




winners 

■ What in the world is this? That's what our Mr. Brain- 
Booster kept asking himself as the postman kept bringing 
him mystery objects and photos sent by Nature and Science 
readers. The objects and photos were entries in the Mystery 
Object Contest announced in the October 14, 1968 issue of 
Nature and Science, and Mr. Brain-Booster's job was to try 
to identify the mystery objects, then pick out the ten "best" 
ones. 

It wasn't easy to identify such things as a piece of chame- 
leon tail, a sheepshead mushroom, a foot massager, or a 
clarinet valve pad. And who had ever seen a ball bearing 
separator, a lobster trap bait bag, an Eskimo yo-yo, or a 
hexahexaflexagon? But the real problem was deciding which 
of the 382 mystery objects should be chosen as winners. 
Was a seagull skull more puzzling than an old-fashioned 
clothespin? Would more readers recognize a wasp stinger 
than a spark plug gapper? Was a worn-out sweeper brush 
"better" than some hair from a peccary? 

Somehow, though, Mr. Brain-Booster made his choices, 
and you can see some of the winning mystery objects here. 
Can you figure out what they are? ■ 

February 17, 1969 



Give Up? 



Turn the page upside down to learn the 
identifications of the mystery objects 
shown, along with the names of the 
readers who submitted the objects or 
photos. 

01$ jo azud 
e P3AI303J paoiBU suosjsd 9iJ} jo qoBg 

(pUDl 

-LiDfti 'yjujpauj 'smu\ioj ui{Of tuojf) 
siuB[d Sui^jbui joj Sbi 3ui[3qBi b • 

(yuo A M3H 'ndiopuDU 'infj 
<Gȣ) iuou}) pjBoq Suiuoji aqj oj uoji dui 
-33J3 ub ujojj pjoo aqj pjoq oj dip b • 

(viosauufi^i 'uapuDXdiy isd/ft 
'uosuiuvm (/;«# utojf) s3[jjoq Bpos oju; }y 
jBqi saqno aoi Suizsajj joj pjoui b • 

:3J3M UMoqs }OU 
3JB }Bqj spafqo AjajsAui 3uiuuia\ JaqJO 

■(DpDA3^l 'SlfJDdS UL\3UQ 

3 ll 3l l J !lM ujojf) japjoq sdijs uouiaj B '/, 

-jopy 'Xi/djrifq ud3$ wcuf) jadsd paxB/W jo 
xoq b ujojj aSpa 3u;un3 dn-pajjoj b 9 

(sioumi 'yjoj 
y/DO '-t03Q ud/DH wcuf) qjnoui s.qsy b 
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13 



A LOO 




A little distance makes a big 
difference in what you see through a 
magnifying lens. With a flashlight and 
some common materials, you can find out why. 

■ Have you ever looked at nearby and distant objects 
through a reading glass or pocket magnifying lens as you 
moved the lens toward the object and away from it, or as 
you moved your eye toward the lens and away from it? 
Try it and you will see that a magnifying lens can make 
objects appear smaller as well as larger, turn them upside 
down, and even make them seem to disappear. 

With a flashlight and some other common materials, 
you can investigate your magnifying lens and find out how 
it does all these different things. To begin with, though, it 
helps to know what a lens does to light beams as they pass 
through it. 



PROJECT 



Put a penny in a bowl, "sight" the penny over the 
tip of your finger, and see if you can put your finger- 
tip directly on the penny. If you keep your fingertip 
moving in the straight line between your eye and the 
penny, you should hit the "bull's eye." Now fill the 
bowl with water, roll up your sleeve, and see if you 
can put your fingertip on the penny on the first try. 
Does it make any difference whether you are sighting 
straight down on the penny or from the side of the 
bowl? 



When you are looking straight down at the penny, a 
beam of light from the penny travels straight up through 
the water and the air to your eye. It follows a straight path 
that crosses the "border" between the water and the air at 
a right angle. 

When your eye is near the side of the bowl, however, 
the light beam from the penny crosses the border at a slant. 
Instead of following the same straight path all the way 
from the penny to your eye, the beam changes direction 
as it crosses the border. Since you are used to receiving 
14 



light in a straight path from an object, the bent beam fools 
you into thinking the penny is where it appears to be, 
instead of where it is. 

The light beam is bent, or refracted, because light travels 
slower in water than in air. Diagram 1 shows what hap- 
pens when the light beam from the penny moves from the 
water into the air at a slant to the border. The light at one 
side of the beam moves into the air and speeds up before 
the light at the other side of the beam gets out of the water. 
With one side moving faster than the other side, the beam 
is turned in the direction of the side that is still in the water. 

Light travels even more slowly through glass than 
through water. So a light beam is also refracted as it moves 
from the air into a block of glass and back into the air 
(see Diagram 2). Because of its shape, however, a magni- 
fying lens refracts light in a special way. Notice that the 
sides of your magnifying lens are curved outward, making 
the lens thickest in the center and thinnest around the edge. 
A lens that is curved this way is called a convex lens. 

Focusing Light Beams 

To see how your convex lens refracts light, wrap a 
piece of aluminum foil around the head of a flashlight so 
that the foil is stretched flat over the flashlight lens. Push 
a sharp pencil point through the foil to make three small 
holes, as shown in Diagram 3. Cover a table with wrapping 
paper or a newspaper, rest the lighted flashlight on a box, 
and pour a little talcum powder onto a sheet of paper. 

Now, with the room darkened, hold the magnifying lens 
so the light from the center hole passes straight through the 
center of the lens, and. gently shake a little powder into the 
air beyond the lens. Looking from the edge of the table, 
you should be able to see the three parallel beams of light 
from the flashlight brought together, or focused, at a single 
point beyond the lens, as shown in the photo. This is called 

1 




# 




/W 



penny 



where penny \y 

appears to be 

A beam from the penny changes direction as it moves from 
water into air, so the penny appears to be where it isn't. 

light beams 



glass 




Light beams passing through a glass block are bent accord- 
ing to the angle at which they cross the "borders." 



.XATLRE AND St //. \< / 



the focal point of the lens, and it may be from a few inches 
to a foot or so beyond the lens, depending on how much 
the sides of the lens are curved. 

A line running through the exact center of each side of 
the lens is called the principal axis of the lens. You can 
see that a light beam that passes through the lens along 
its principal axis is not bent at all. But light beams that 
are traveling parallel to the principal axis are brought to- 
gether at the focal point of the lens. (Do you think the 
lens has a focal point on both sides? Turn the lens around 
and see if the light beams are brought together at the 
same distance from it. ) 

The distance from the focal point to the center of the 
lens is called the focal distance of the lens. It's hard to 
measure in the dark, but you can measure it easily by 
focusing the light from a distant tree or house on a sheet 
of paper held behind the lens (see Diagram 4). Move the 
lens toward the "screen" and away from it until the image, 
or picture, on the screen is as sharp as you can get it. The 
distance from the center of the lens to the screen is the 
focal distance of the lens. 

With this information and a tabletop at least four times 
as long as the focal distance of your lens, you can find out 
how different kinds of images are formed by your lens. 
Fasten a piece of white paper over the head of your flash- 
light with a rubber band so the paper is flat over the flash- 
light lens. Use a marking pen or crayon to draw a large 
arrow on the flat circle of paper (see Diagram 5). 

Cover the table with paper. Place the flashlight on a few 
books at one end, and a white paper screen supported by 
a book at the other end. You might think the lighted flash- 
light would project an image of the arrow on the screen. 
Darken the room and you will see that it merely lights the 
screen a bit, without forming an image of the arrow. Re- 
member that light beams are moving out in all directions 
from each point on the flashlight face. At least two beams 
from the same point on the flashlight face must be brought 
together at the screen to form an image there. 

Use some modeling clay to stand your lens near the 
middle of the table. On each side of the lens, measure the 
focal distance of the lens and mark it F on the paper. 
Also mark 2F at twice the focal distance on each side of 
the lens, as shown in Diagram 5. 

With the flashlight face several inches beyond 2F on 
one side of the lens, move the screen between 2F and F 
on the other side until a sharp image of the arrow forms 
on the screen. Diagram 6 shows how the image is formed. 

Now move the flashlight face to position 2F on one side 
of the lens and the screen to 2F on the other side. What 
happens to the image? Can you draw a diagram to show 
how this image is formed? 

(Continued on the next page) 

February 17,1969 



principal axis 
of lens 




Beams moving parallel to the principal axis of a convex lens 
are brought together at its focal point beyond the lens, as 
shown in the diagram and photo . 





When a sharp image of a distant scene forms on the sheet of 
paper, it is at the focal distance from the lens. 



paper 




With flashlight and screen as shown above, an image forms 
on the screen as shown below. Beam A moves parallel to the 
principal axis of the lens, so it is bent through the focal point 
on the other side. Beam B moves through the focal point on 
one side, so it leaves the lens moving parallel to the principal 
axis. Where A and B meet, an image is formed of the point on 
the flashlight face where both beams started. Can you draw 
in the paths of Beams C and D from the lens to the screen? 




2F 



image 



15 



A Look at Lenses (continued) 

Try placing the flashlight face between 2F and F and 
move the screen back and forth on the other side of the 
lens until a sharp image of the arrow is formed. (A slide 
projector works this way, and you can see why the slide 
must be placed upside down in the projector.) Can you 
diagram the paths of light beams that form this image? 

Do you think that an image will form if you place the 
flashlight face at F, or closer to the lens? Try it and see. 
Can you explain your findings? 

Suppose you put your eye in place of the screen in each 
of the above investigations. Try it with the arrow at each 



2F 



^l 




virtual 
image 



With an object between F 

and the lens, your eye sees 

an enlarged virtual image of 

the object through the lens. 



of the places you tried before. Move your head back and 
forth just as you moved the screen to sharpen the images. 
Be sure to look for an image with the flashlight face 
placed between F and the lens. The image you see will be 
familiar, but different from the real images that you have 
been looking at. This one is called a virtual image, because 
it doesn't form on a screen. Diagram 7 shows how .this 
image is formed. Does it remind you of the penny you saw 
where it wasn't in the bowl of water?— F.K.L. 




eyepiece 



real 
image 



distant 
object- 



16 



If you have two magnifying lenses with different 
focal distances, you can make a simple refracting 
telescope (see "Big Eyes on Space," N&S, February 
3, 1969) and a microscope. 

Hold the lens with the longer focal distance at 
arm's length, pointed toward an object across the 
room from you. Now hold the other lens to your eye 
and look through both lenses, moving the first lens 
back and forth until you can see the object clearly. 
What you see is a magnified virtual image of the real 
image projected by the first lens (see diagram). 

By looking at the object through the telescope with 
one eye and at the same time with your unaided eye, 
you may be able to line up the image with the object 
and guess about how many times the telescope "en- 
larges" the object. You can figure out the magnifying 
"power" of your telescope more exactly, however, by 
simply dividing the focal distance of the eyepiece 
lens into the focal distance of the objective lens, at 
the far end of your telescope. 

Now hold the lens with the shorter focal distance 
(the objective lens for the microscope) near these 
words to form an enlarged real image (upside down) 
of them at your eye. Hold the second (eyepiece) lens 
near your eye and move it up and down until you see 
an enlarged virtual image of the real image (see dia- 
gram). 

The magnifying power of your microscope is harder 
to figure out than that of the telescope. To begin with, 
you have to find the distance of the real image from 
the objective lens and divide that figure by the focal 
distance of that lens. This tells how many times the 
real image is bigger than the object being viewed. 
Then you have to multiply this figure by the number 
of times the eyepiece lens enlarges the real image 
to find out how much bigger the object appears when 
viewed through your microscope. 



eyepiece 
lens 




Using This Issue . . . 

(continued from page 2T) 

particular distance beyond the lens. 

If the "object distance" is much 
larger than the focal distance (F), 
the "image distance" is about equal to 
F. If the object distance is greater than 
2F, the image is smaller than the ob- 
ject. When the object distance is 2F, 
an image the same size as the object 
forms at 2F. When the object is be- 
tween 2F and F, a larger image is 
formed someplace beyond 2F. 

When the object is at F or closer 
to the lens, no real image is formed, 
because beams of light from each point 
on the object are not brought together 
at a single point beyond the lens. 

However, with the object at F or 
closer, your eye can see through the 
lens an enlarged image of the object 
(Diagram 7). This is called a virtual 
image because it is just an effect caused 
by the refraction of light beams from 
the object— not a real image formed by 
beams of light from the same point 
that meet on a screen. 

Topics for Class Discussion 

• Why should a distant object be 
used to find the focal distance of a lens? 
By moving an object farther and far- 
ther away from a lens with a long focal 
distance (1 foot or so), your pupils 
will find that the image distance gets 
closer and closer to the focal distance 
of the lens. By diagraming this case, 
your pupils can see that the farther the 
object is from the focal point of the 
lens, the closer the beams of light from 
each point on the object come to reach- 
ing the lens parallel to its principal 
axis. And beams parallel to that axis 
converge at F beyond the lens. 

• Why doesn't the flashlight project 
an image on the screen when no lens 
is between them? The light beams from 
each point of the flashlight face reach 
the screen at all different places, so the 
screen is lighted, but no image is 
formed. 

• How, then, can you see the arrow 
on the flashlight face? The convex 
lens of your eye forms an image of 
the flashlight face and arrow on the 
retina, or "screen" in the back of your 
eye. This is a real image, much smaller 

February 17,1969 



than the object, and upside down. (The 
image is changed into electrical signals 
and carried by the optic nerve to 
your brain, which "reads" the signals 
so that you "see" the object rightside 
up.) 

• Since the image distance in your 
eye is always the same, how can you 
see objects at different distances so 
clearly? The eye lens is soft, and can 
be stretched or squeezed by the eye 
muscles to make it thinner or fatter, 
changing the focal distance to fit the 
object distance. (Have your pupils 
move a finger to one eye and see where 
it begins to appear fuzzy because the 
eye lens can't be squeezed any fatter.) 

• Why do many people need eye- 
glasses to help them see clearly? The 
diagram below shows how nearsight- 
edness is corrected with concave (in- 
ward curving) lenses and farsighted- 
ness with convex lenses. Astigmatism 
(blurry vision due to irregularities in 
the eye lens) is corrected by an an- 
astigmatic lens, shaped irregularly to 
compensate for the eye lens. 



eye with normal vision 



iR 



nearsighted eye 




corrected with 
concave lens 




farsighted eye 




corrected with 
convex lens 




Activity 

Your pupils can make a water lens 
by bending a paperclip around a nail 
to make a tiny ring. Dipped in water, 
the ring picks up a tiny, convex- 
shaped drop. A larger drop, convex on 
top only, can be held on a piece of 
cellophane fastened flat over a round 
hole in a piece of cardboard. Both 
work as a magnifying lens. Can your 
pupils find the focal distances of these 
lenses? 

Bra in- Boosters 

Mystery Photo: The photo shows 
lobster traps stacked up on a wharf. 



What will happen if? Have your 
pupils try to guess the answers to 
these questions and explain them. 
Then set the jars where the sun can 
shine on them for several hours. The 
temperature in the "empty" jar will 
rise fastest; it takes less heat to raise 
the temperature of air than to raise the 
temperature of an equal volume of 
water the same number of degrees. 

After the jars have been allowed 
to reach their maximum inside tem- 
peratures, the thermometer in the 
colored water should show the highest 
reading. The colored water will ab- 
sorb more heat than clear water (or 
air) absorbs. Some pupils might try 
putting other liquids or materials, such 
as sand or soil, into the jars, and report 
on which heat up fastest and which 
reach the highest temperature in sun- 
light. 

For science experts only. The sewer 
line in a house is vented with an open 
pipe, or stack, that sticks out through 
the roof (see diagram). When wind 



wind_ 




blows across the top of the stack, the 
air pressure down the stack is de- 
creased. Normal air pressure inside the 
house then pushes the water down 
lower in the toilet and it rises in the 
stack. When the wind dies down, air 
pressure in the stack returns to nor- 
mal or near-normal, pushing the water 
in the stack down, and the water in 
the toilet up. On a windy day, small 
changes in wind velocity can keep the 
water level in the toilet constantly 
(Continued on page 4T) 

3T 



Using This Issue . . . 

(continued from page 3T) 

fluctuating up and down. 

The changes of air pressure inside 
the stack are examples of the Bernoulli 
effect: As a fluid flows faster, it exerts 
less outward pressure at right angles 
to its direction of flow. Another exam- 
ple is shown here: 







Can you do it? An easy way to get a 
can just half full of water is to fill 
the can, then pour off water slowly 
until the water level just reaches the 
bottom of the can (see diagram). The 
can should now be half full. You can 
check this by pouring 
the water from the 
can into a separate 
container, half-filling 
the can again by the 
same method, and then pouring the 
water from the second container back 
into the can. If the can was filled half 
way each time, it should now be full. 

Fun with numbers and shapes. Here 
is how five 5s may be arranged to pro- 
duce each of the numbers 2 through 12: 




5+5 
5 

5+5+5 



5+5 = 2 



| + f + 5=7 



5 5 

5+5+5+5 



= 3 



5+5+5 



= 4 



55 
55 

55 
55 



X 5 = 5 



+ 5 = 6 



5 
55-5-5 



55 5 
5 + 5 

55 

¥- 5 + 



+ 5 = 8 



= 9 



10 



5= 11 



^+^ = 12 
5 + 5 



Can your pupils produce other num- 
bers with five 5s, or produce 1 through 
1 2 with several of another number? 

Just for fun. The "hose trombone" 
described works on the principle that 
the shorter the length of a column of 
air, the higher pitched sound it pro- 
duces when the air is set in vibration 
(as by blowing). 

4T 




Prepared under the 
supervision of The 
American Museum 
of Natural History 



wall charts 

from 
nature and science 



Let your classroom walls help you teach with a completely new set of 10 Na- 
ture and Science Wall Charts. Reproduced from the pages of Nature and 
Science— and enlarged 300% in area— these Wall Charts cover a range of sub- 
jects that your science class should know about. 

For chalkboard, bulletin board, wall— for science exhibitions and displays— 
here are lasting sources of information that are always ready to catch (and 
educate) the wandering eye of any student. 



* all fully illustrated in vivid color 

* printed on durable, quality stock 

* each chart an abundant 22 by 34 inches 

* delivered in mailing tube for protection and storage 



Six Ways to Success — describes six 
ways in which plants and animals are 
adapted to insure survival of the species. 

Travel Guide to the Sun and Its Planets 

— depicts our solar system,showing rel- 
ative sizes of the planets, number of 
satellites, temperature, diameter, dis- 
tance from sun. 

The "Spirit" That Moves Things — ex- 
plains what energy is, where it comes 
from, and how it can change form. 

History in the Rocks — cross section of 
Grand Canyon shows how each geo- 
logical stratum was formed and illus- 
trates some representative fossils from 
each period. 

Spreading the Word — depicts how man 
has communicated information from 
one place to another through the ages. 



Visit to a Plant Factory — shows how 
green plants make their own food and 
how the food is transported to their 
parts. 

Rabbit Rollercoaster — illustrates the 
annual population cycle of the cotton- 
tail and describes why few rabbits live 
as long as a year. 

How Diseases Get Around — diagrams 
ways in which diseases are spread and 
shows how vaccines protect against 
disease. 

Who Eats Whom — explains the ecol- 
ogy of the sea and some of the links in 
its "food chains." 

The Horse's First 55 Million Years — 

museum reconstructions in a time-line 
presentation illustrate the evolution of 
the horse. 



Imagine your pupils' excitement as you display a different chart each month 
of the school year. Order a complete collection of ten for only $7.50. 

To order, use postpaid order form bound into this issue. 



nature and science 

TEACHER'S EDITION 

VOL. 6 NO. 12 / MARCH 3, 1969 / SECTION 1 OF TWO SECTIONS 

COPYRIGHT © 1969 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 



Putting Our Hows and 
Whats in Order 

by Roy A. Gallant 



■ Whatever the reasons, a youngster 
who is looking for a science book to 
read usually heads for the astronomy 
shelf first. Unfortunately, however, too 
many of the astronomy books he finds 
turn out to be unimaginative (and un- 
informed) descriptive essays dealing in 
an abstract way with the diameters, 
distances, atmospheric compositions, 
and so on of the planets or the stars; 
and, of course, how it all began; and, 
inevitably, the expanding universe. 
Also, usually there is a lavish display of 
"gee-whiz" illustrations whose cap- 
tions too often miss the point. Never- 
theless, space and astronomy books for 
young people continue to be science 
best sellers. 

What saddens me most about such 
books is that the youngsters are being 
cheated. The real excitement is not the 
fact that the giant star Betelgeuse, for 
instance, is a red giant with a diameter 
400 times that of the sun (wow!), but 
in how astronomers think that Betel- 
geuse got that way, and what will hap- 
pen to it next. In the hands of an 
imaginative and informed author, there 
is the topic for a whole book, a "gee- 
whizzer" in the best sense of the ex- 
pression, an intellect-stretcher, rather 
than a fancy-tickler. It's a matter of 
putting the "how" before the "what." 

A few years ago I was privileged to 
be a member of the University of Illi- 
nois group preparing astronomy mate- 
rials for the middle elementary grades. 



Roy A. Gallant, consulting editor to N&S, 
is the author of about 20 science trade books 
and textbooks for young people. 



In our teacher's guides we made the 
following point: 

"The modern astronomer's work ex- 
emplifies many facets of scientific in- 
quiry. But unlike the biologist or 
chemist, the astronomer is far removed 
in both space and time from the objects 
of his study. Because of this problem, 
the astronomer must use fully every bit 
of information he can obtain in order 
to construct a satisfactory theory. In so 
doing, long lines of reasoning are 
sometimes employed in order to inter- 
pret the observational data." 

In my article on page 6 of this issue, 
I have tried to reflect this approach to 
astronomy teaching by writing a very 
brief, and therefore necessarily super- 
ficial, account of how men over the 
centuries have searched for an under- 
standing of what the stars are made of 
and what keeps them shining. 

Analyzing a Star's Light 

Just about everything we know 
about stars has been learned by ana- 
lyzing their light with spectroscopes 
(see Glossary, page 4T). By the use of 
a prism or a diffraction grating, a spec- 
troscope analyzes the light from a star 
by separating that light into its com- 
ponent colors, or wavelengths. 

If you look at a candle flame or a 
light bulb through a piece of grating, 
you see a continuous spectrum; that is, 
you see all of the colors from violet to 
red, each color smoothly blending into 
the next. 

If you hold a bit of sodium, a bit of 

iron, a bit of gold, or a bit of any other 

element in a flame and vaporize the 

(Continued on page 4T) 




IN THIS ISSUE 

(For classroom use of articles pre- 
ceded by •, see pages 2T and 3T.) 

Strange Tricks of Memory 

Your pupils can find out how they 
remember certain things and forget 
others, then test each other's ability 
to remember. 

• Brain-Boosters 

• The Private Life of a Star 
The Birth and Death of Stars 

A well-known author of astronomy 
books for young people explains how 
stars like the sun form and develop, 
and what astronomers think happens 
to them. A Wall Chart presents 
the process visually. 

• The Catnip Chemical 

A biologist finds out how this sub- 
stance may help the plants that pro- 
duce it to survive. 

Secrets of Kure Island 

A biologist tells how he studied the 
behavior of the birds on a tiny Pa- 
cific isle. 

Does Cold Help Cause Colds? 

Not directly, an experiment indi- 
cates; but it may be an indirect fac- 
tor. 



IN THE NEXT ISSUE 

V/hat's being done to kill off — and 
to save — whales . . . Human reac- 
tions to sonic booms . . . How scien- 
tists use "superior" trees to improve 
the species ... A Science Work- 
shop in dissolving solids and taking 
them out of solution. 



USING THIS 

ISSUE OF 

NATURE AND SCIENCE 

IN YOUR 

CLASSROOM 



Private Life of a Star 

You will not have any trouble con- 
vincing your pupils that the sun and 
other stars have been shining for a 
"very long time," at least by human 
standards. The stars in the constella- 
tions that we see tonight are much the 
same as when they were plotted by 
Arabian, Egyptian, and Greek astron- 
omers several thousand years ago. 

Your pupils may wonder how fossil 
evidence shows that the sun has been 
shining for hundreds of millions of 
years with about the same intensity. 
During the Ordovician Period (about 
500 million years ago), there was a 
marine organism known as lingula. 
The organism persists to this day, rela- 
tively unchanged through that vast 
stretch of time. That and many other 
examples that can be drawn from the 
evolutionary record are pretty con- 
vincing evidence that the sun's radia- 
tion output has been essentially the 
same for at least 500 million years. 

An explanation for the constancy of 
the sun's radiation over so long a time 
could not be offered until Albert Ein- 
stein showed that matter can be 
changed into energy according to the 



NATURE AND SCIENCE is published for The American 
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nightly September, October, December through March; 
monthly November, April, May, July (special issue). 
Second Class postage paid at Garden City, N.Y. and at 
additional office. Copyright © 1969 The American 
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New York, N.Y. 10024. 



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equation E=mc 2 (energy equals mass 
times the square of the velocity of 
light). This made it possible for scien- 
tists to figure out how, when hydrogen 
nuclei fuse, a small amount of mass is 
changed into radiant energy (see "En- 
ergy from Fusion"). 

In these reactions, four hydrogen 
nuclei are converted into one helium 
nucleus, but its mass is slightly less 
than the total mass of the four hydro- 
gen nuclei. What has happened is that 
0.007 (seven-tenths of one per cent) of 
the mass of the hydrogen taking part in 
the fusion is changed into energy, while 
0.993 (99.3 per cent) of the mass is 
changed into helium. 

The energy from a single fusion re- 
action is just about what a mosquito 
uses to "take off" from your neck. But 
when you add up the energy from the 
vast number of fusion reactions taking 
place every second, the energy output 
is enormous. Equally important, the 
mass remaining is sufficient to keep the 
star shining for billions of years. 

Energy from Fission and Fusion 

Some of your pupils may ask: Is the 
fusion process that keeps stars shining 
the same as the fusion process in a 
hydrogen bomb? Essentially, yes. 
Some may also wonder whether this is 
how the "atomic" (uranium) bomb 
and nuclear power plants produce en- 
ergy. It is not. 

Energy is obtained from the heavy 
element uranium by a process called 
fission, or "splitting." In the uranium 
bomb, two masses of U 235 are brought 
together to make a "critical" mass— a 
mass large enough so that a "chain re- 
action" begins to take place. In a 
critical mass of U 235 , free neutrons col- 
lide with the uranium atoms, splitting 
them and releasing some of the energy 
that holds them together. Each split 
atom releases two new neutrons, each 
of which is free to split another atom of 
U 235 , and so on. This chain of reactions 
takes place quickly and violently, re- 
sulting in an explosion. 

A chain reaction of U 235 can be 
slowed down to produce a continuous 
supply of energy, rather than a single 
powerful blast. This can be done by 
inserting carbon rods into the mass of 
U 235 to intercept many of the free neu- 



trons that would otherwise split ura- 
nium atoms. Energy produced in this 
way is usually used to heat water, mak- 
ing steam to turn generators that pro- 
duce electrical energy. 

Scientists are trying to find a way 
to slow down the fusion process so that 
it releases energy gradually, instead of 
in a single blast. If this can be achieved, 
it will offer two great advantages over 
energy production by fission: 1) a 
much larger, and probably cheaper, 
"fuel" supply (deuterium from the 
nearly limitless supply of heavy water 
in the oceans, as opposed to uranium 
ore) , and 2) no radioactive wastes like 
those from the fission process that pose 
difficult disposal problems. 

(Continued on page 3T) 

ENERGY FROM FUSION 




® + ®-»®*+£ +e- 



gamma ra 



STEP 1: Two protons, or hydrogen nuclei 
(H 1 ), collide and fuse into a nucleus of 
heavy hydrogen, or deuterium (H ! )- In the 
process, one of them loses its electrical 
charge and becomes a neutron. The charge 
is carried away by a positron (e')~ a posi- 
tively charged particle with the mass of 
an electron. A high-energy photon, or 
gamma ray, is the major energy packet re- 
leased by this initial fusion. Also released 
is a neutrino, a tiny particle without an 
electrical charge. As the diagram shows, 
the positron collides with a free electron 
(e~). The two annihilate each other and 
are changed into another gamma ray. 



m 



gamma ray 



©•■»-©- 

//*y h'-vH*** energy 

STEP 2: The new deuterium nucleus fuses 
with a free proton, forming the nucleus of 
a light helium atom (He') and releasing a 
gamma ray of energy. 



«$ + •$ 



He 3 */!*?- 



( (J) gamma ra 

sr © 



2T 



Ht* -r- H'+H'-t energy 

STEP 3: What usually happens next is that 
two lightweight helium nuclei fuse and 
produce the nucleus of an ordinary helium 
atom (He'). In the process, two protons 
are freed and so made available for other 
fusions, and one gamma ray of energy is 
released. 

NATURE AND s< II \< I 



M 



nd science 



VOL. 6 NO. 12 / MARCH 3. 1969 J Don't forget tO . . . 

• see page 2 

^^ m ^ ^^ ^^ • STRANGE TRICKS 

If Al 14 Af 1 ! OFMEMORY 



V 




HOW LONG 
WILL THE SUN 
KEEP SHINING? 
see page 6 



The Private Life of a Star 






BQEM 









nature and science 

VOL. 6 NO. 12 / MARCH 3, 1969 

CONTENTS 

2 Strange Tricks of Memory, 

by Robert M. Goldenson 

5 Brain-Boosters, by David Webster 

6 The Private Life of a Star, 

by Roy A. Gallant 
8 The Birth and Death of Stars, 
by Roy A. Gallant 

1 2 The Catnip Chemical, by Susan J. Wernert 

1 3 What's New?, by B. J. Menges 

14 Secrets of Kure Island, 

by Alan H. Anderson, Jr. 
1 6 Does Cold Help Cause Colds?, 
by R. J. Lefkowitz 



PICTURE CREDITS: Cover, pp. 7, 10, 11, photographs from the Mount Wilson 
and Palomar Observatories; p. 3, Frederic Lewis, Inc.; p. 5, photo by David 
Webster; pp. 5, 7-9, 11, 12. drawings by Graphic Arts Department, The Ameri- 
can Museum of Natural History, p. 6, photograph fom the Lick Observatory; 
p. 12, photo by Thomas Eisner; p. 13, top photo by Laurence Pringle. bottom 
photo courtesy of Cartwright Aerial Survey Inc.; p. 14 (top), 15 (bottom) photos 
by Alan H. Anderson, Jr.; p. 14, bottom photo by William Wirtz: p. 15, top 
photo by Alfred M. Bailey and R. J. Neidrach from National Audubon Society; 
p. 16, Donald B. Clausen. 



PUBLISHED FOR 

THE AMERICAN MUSEUM OF NATURAL HISTORY 

BY THE NATURAL HISTORY PRESS 

A DIVISION OF DOUBLEDAY & COMPANY, INC. 

editor-in-chief Franklyn K. Lauden; executive editor Laurence P. 
Pringle; associate editor R. J. Lefkowitz; assistant editors Mar- 
garet E. Bailey, Susan J. Wernert; editorial assistant Alison New- 
house; art director Joseph M. Sedacca; associate art director 
Donald B. Clausen • consulting editor Roy A. Gallant 

publisher James K. Page, Jr.; circulation director J. D. Broderick 
promotion director Elizabeth Connor 
subscription service Frank Burkholder 

NATIONAL BOARD OF EDITORS 

PAUL F. BRANDWEIN. CHAIRMAN, Dir. of Research. Center for Study of 
Instruction in the Sciences and Social Sciences, Harcourt. Brace & World, Inc. 
J. MYRON ATKIN, Co-Dir., Elementary-School Science Project, University of 
Illinois. THOMAS G. AYLESWORTH. Editor, Books for Young Readers, 
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San Fernando (Calif.) State College. GERARD PIEL, Publisher. Scientific 
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Education. WILLIAM P. SCHREINER, Coord, of Science. Parma (Ohio) Citv 
Schools. VIRGINIA SORENSON, Elementary Science Consultant, Dallas In- 
dependent School System. DAVID WEBSTER. Staff Teacher, Elementary 
Science Study, Education Development Center, Newton, Mass. • REPRE- 
SENTING THE AMERICAN MUSEUM OF NATURAL HISTORY: FRANK- 
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HARRY I.. SHAPIRO, Curator of Physical Anthropology. 

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served. Printed in U.S.A. Editorial Office: The American Museum of Natural History, 
Central Park West at 79th Street, New York, N.Y. 10024. 

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mmmt workshop 



Do you have a photographic memory? 
Have you ever gone to some entirely new 
place and remembered being there 
before? Scientists have 
studied some of these . . . 



STRANGE 
TRICKS 
OF 



MEMORY 



by Robert M. Goldenson 



■ The Olsen family was hopelessly lost. After driving 
what seemed like miles, they finally passed an old farr 
house. John, the older son, went in to ask the way. A fe 
minutes later he returned with a puzzled expression on h 
face. "I got the directions all right," he said, "but somi 
thing very strange happened. When I went into the liviij 
room, I was sure that I had been there before. I know ilj 
impossible, but I can't get this queer feeling out of nj 
head!" 

The "feeling of having been there before" is so commc 
that it has been given a special name. It is deja vu, which 
French for "already seen." People have been trying \ 
explain deja vu for more than 2,000 years. 

Psychologists who study how people think and behav 
have two possible explanations. One is that the deja vu 
something that has happened to you before— but not in tr 
exact same way. People usually remember in a general w 
what they see and hear, but they seldom remember the d 
tails. If something like it happens again, they may thi 
that they have been through the whole experience befor 

John, for example, had never seen that actual livi 
room before, but he might have seen a room— or a pictu 
of a room— with the same general look. Perhaps the furn 
ture had been arranged in the same way. And this mad 
the entire room seem familiar to him. 

The second explanation is that John might have see 
the room in a dream. Our dreams are made of bits an 

Dr. Robert M. Goldenson, a psychologist, is the author of Al 
About the Human Mind, for young readers, and Encyclopedia o 
Human Behavior. 

NATURE AND SCIENCE 



tt 



pieces of what we have actually seen and heard. A picture 
; put together in one of John's dreams might have been very 
imuch like the farmhouse room, and what he had merely 
idreamed about appeared to be a real experience. Nowon- 
:der it seemed so mysterious! 

Psychologists have tested the idea that dreams seem to 
become real. They described a building in great detail to 
several people who were in the sleep-like condition called 
hypnosis. A few days later, the people visited that building, 
which they had never seen before. And, sure enough, most 
of them remarked, "You know, I have a queer feeling I've 
been here before!" 

| Forgetting 

Memory sometimes plays a trick that is the very opposite 
of the deja vu: People or things look strangely imfamiliar. 
We're sure we have never seen them before, even though 



:' 



DO YOU HAVE A PHOTOGRAPHIC MEMORY? 

You can use this photo, or one something like it from a mag- 
azine or newspaper, to find out whether you have a photo- 
graphic memory. A good test photo shows a number of 
different objects, signs, and people doing different things. 
Have someone use a watch with a sweep second hand to 
time you as you look at the photo for just 20 seconds. When 
the time is up, look away, close your eyes, and try to picture 
the scene as quickly as you can. Describe exactly what you 
see, and have your helper write down what you remem- 
bered. Compare the list with the photo to see how well you 
remembered what you saw. 




*ww 



h 



m 




K 



s 



we really have. This experience is called jamais vu, French 
for "never seen." 

The simplest example is failing to recognize someone we 
ought to remember. Think back to the last lime this hap- 
pened to you. Ask yourself how you feci about the person 
you did not recognize. You'll probably find there is some- 
thing about him you dislike very much, or else there was 
a bad experience connected with him in some way. 

We tend to protect ourselves from something unpleasant 
by blocking it from our minds. For example, a boy might 
have a terrible time remembering the name of a teacher 
who had scolded him many times in the classroom. The 
odd thing is that we don't really try to block out unpleasant 
memories. Something deep inside our minds does it for us. 

Psychologists have tested this blocking, too. In one ex- 
periment, they asked a group of young people to write 

(Continued on the next page) 



MEMORY, 



« UP 






1 • *.' • »■ 


• 


. ] « hioh • 











94 




V10RY 



Strange Tricks of Memory (continued) 

down the five most pleasant and the five most unpleasant 
experiences each had had within the past few months. Their 
lists were kept in a file for one year, then each person was 
asked to recall as many of the experiences on his written 
list as possible. The people usually remembered almost 
twice as many of the pleasant happenings as the unpleasant 
ones. They had automatically protected themselves from 
the unpleasant experiences by forgetting them. 

Few Photographic Memories 

Try the memory test that is described in the photo cap- 
tion on page 3 . You'll probably be able to remember the 
picture fairly clearly, and you'll give quite a few details. 
But you'll overlook many others, or give some wrong ones. 
If so, you have a rather normal memory. 

But if you happen to be one of those unusual people with 
what is sometimes called a "photographic memory," here 
is what will happen. You'll see the picture so clearly that 
the scene will appear to be right in front of you, not simply 
a picture in your imagination. You'll probably be able to 
read off the signs in the photo forward or backward, not 
just remember them. And, most surprising, you'll be able 



PROJECT- 



Does the meaning of words make any difference in 
how fast you can memorize them? Have someone 
time you with a stopwatch, or a watch with a sweep 
second hand, as you memorize the words in List A. 
How long does it take you to memorize the list so that 
you can repeat it once correctly? Do the same thing 
for Lists B and C, waiting a few minutes between lists. 
Which list did you memorize in the shortest time? 
Which took the longest? Can you explain why? 

See if you can work out a "system" for memoriz- 
ing a list of words like those in Lists B and C, as sug- 
gested in this article. 



List A 


List B 


ListC 


DAX 


PAPER 


STAR 


KIV 


FENCE 


GRASS 


YOR 


LAMP 


OWL 


ZEP 


MEAT 


SHELL 


NAL 


SKY 


TREE 


MIZ 


TWIN 


ELK 


CEF 


HUT 


SAND 


GAH 


TRAIL 


PLANT 


BIS 


BOTTLE 


BAT 


QOP 


CLAY 


SEA 



to "enlarge" part of the picture and describe details you 
didn't seem to notice when you stared at the photograph. 

About one out of 10 or 20 children has this amazing 
ability of photographic memory, but most lose it by the 
age of 9 or 10. Sometimes, though, it lasts into adult life. 
President Theodore Roosevelt must have had it, for he was 
able to look at an entire newspaper page for just a few 
moments and then repeat everything on it, word for word. 
The ability is also found in many mathematical "whizzes" 
who can multiply large numbers in their heads very 
quickly. Such a person sees the numbers as if they were 
written on a blackboard. Then he quickly does one part 
of the problem and leaves it on his "blackboard" while he 
works on another part. 

You've probably heard about people who perform 
amazing feats of memory for audiences. They can repeat 
the names of 50 people in the audience, or recall hundreds 
of dates after hearing them only once. A few of these 
memory experts have photographic memories, but even 
this isn't enough to explain their ability. How can it be 
explained? 

Try To Remember 

First, they were probably born with an unusually good 
ability to remember, just as some people are born with 
the ability to become good musicians. Second, often they 
have discovered early in life that they have better mem- 
ories than most people. Because other people admire them 
for the tricks they can perform, they spend a great deal of 
time working with numbers or memorizing names. And 
third, they usually use some kind of "system," which they 
practice very often. 

Some of these people try to find ways to connect a name 
with something they already remember; for instance, 
"Mr. Mason" might remind them of the Masonic Lodge. 
Others make a "mind picture" based on the name. For 
example, when they hear "Mr. Donaldson," they picture 
Donald Duck with a duckling trailing after him. When they 
see the man again, they are reminded of the duckling pic- 
ture and have little trouble in remembering the name— 
unless they call him "Mr. Duck!" 

Many people can perform surprising feats of memory if 
they work hard enough at it. But the real question is 
whether it is worth all the effort. Usually they can recall 
only a lot of details that don't mean much. Their memory 
tricks dont apply to things that count, like important ideas 
of science and history. 

There is really only one way to remember such ideas. 
That is to study them until you understand them. That's 
the secret of a good memory. For if you look for the mean- 
ing behind the facts, you won't need a photographic mem- 
ory or any special tricks at all ■ 

NATURE AND SCIENCE 




prepared by DAVID WEBSTER 

FOR SCIENCE EXPERTS ONLY 

A balloon filled with helium was floating on a string outdoors. 
Then it began to rain, and the balloon fell to the ground. Can 
you explain why? 

JUST FOR FUN 

Get some soil that has no plants growing in it, and keep it 
watered for a few weeks. Does anything grow? 




MYSTERY 
PHOTO 

Why are all the branches 
growing out from only 
one side of this 
pine tree? 



WAX DROP 



□ 




□ 




□ 



FUN WITH NUMBERS AND SHAPES 

Around the lake are four big houses and four little houses. 
The people in the little houses want to build a fence to keep 
the people in the big houses away from the lake. But the 
people in the little houses want to be able to get to the lake 
themselves. Can you draw a line to show them how to build 
their fence? 

CAN YOU DO IT? 

Can you make an ice cube of three different colors? 

Submitted bv Edie Pullman, New York, New York 




STICKY TAPE 
~^-T= 



ZXZEZZ 



6 



#X 



CANDLE 



WHAT WILL HAPPEN IF? 

Cut small pieces of aluminum foil into the three shapes 
shown here. Then put drops of wax on the ends of each strip. 
Attach sticky-tape "handles" and heat each strip at the cen- 
ter, as shown. Can you guess which end of each strip will 
heat up faster and melt the wax? 



ANSWERS TO BRAIN-BOOSTERS IN THE LAST ISSUE 



What will happen if? The thermometer in the jar without any 
water will go up fastest when the jars are put in sunlight. After 
three hours the thermometer in the colored water will probably 
show the highest temperature. Would an empty jar with a cover 
get even hotter? 

Can you do it? One way to get a can exactly half 

full of water is to fill the can, then slowly tip it to 

pour some of the water out. When the water level 

| just reaches the bottom of the can, the can should 

t be just half filled. How could you check to see if it 

i really is? 

For science experts only: The sewer line in a house is vented with 
an open pipe that sticks out through the roof. When wind blows 
across this pipe, it lowers the pressure of the air in the pipe, so 
the pressure of the air inside the house pushes the water farther 
down in the toilet. 




Mystery Photo: The photo shows a stack of lobster traps. 

Fun with numbers and shapes: Here are ways to arrange five 5s to 
equal the numbers from 2 through 12. What other numbers can 
you make with five 5s? 



5+5 



5 

5+5 + 5 
5 5 



—5+5=2 



"= =3 



5+5+5+5 

5 
55 
55 X5 = E 



= 4 



55 
55 



+ 5 



55 
5 




55-5-5 



5 = 8 



= 9 



55 
5 

55 



4 = io 



-5+5=11 



12 



The Private 




N^: 







■ Have you ever wondered how old the sun is? Or other 
stars? Some people in the past have thought the stars were 
"ageless"— shining forever without beginning or end. But 
with modern telescopes (see "Big Eyes on Space," N&S, 
February 3, 1969), astronomers have found what they 
think may be the "birth-yards" of stars, stars in different 
stages of "life," and stars that are "dying." 

Some kinds of stars are different from others, but this 
article tells how a star like our sun probably forms, passes 
through various stages of its "life," and eventually "dies." 

Bonfires in the Sky 

The sun gives off heat and light. Your senses tell you 
that. Certain Greek astronomers 2,500 years ago reasoned 
that the sun and other stars are fire. Around 500 B.C., 
Heraclitus supposed that the sun was a bowl of "moist 
vapor." Each morning it rose out of the sea and caught 
fire, he said. In the evening it returned to the sea, and its 
fire went out. 

Others supposed that the sun and other stars were globes 
of hot iron. Maybe they got that idea from watching the 
fiery trails of meteors, or "shooting stars," and sometimes 
finding their remains, called meteorites. Some meteorites 
are made of iron, so you can see why people got the idea 
that the stars might be molten iron. 



ABOUT THE COVER 

This photo shows the churning clouds of hot hydro- 
gen that make up the surface of the sun, our nearest 
star. The nuclear reactions inside the sun that keep it 
shining heat the surface gas to about 12,000 degrees 
Fahrenheit. At that temperature hydrogen glows with 
the reddish light by which this photo was made. Dark 
spots on the photo are the tops of clouds that are 
cooler. 



New stars are formed in clouds of glowing gas and dust that 
are called nebulae. This photo shows the Great Nebula in the 
constellation of Orion. You can see it without a telescope 
(see diagram on page 11). 

The idea that the sun and other stars are fiery globes 
hung on for about 2,500 years. Before it could be dis- 
proved, the sciences of chemistry and physics had to grow 
up. 

Let's take a closer look at the idea of a sun that burns, as 
fire does. By reading accounts of day-to-day life written by 
the ancient Greeks and Romans, we know that the sun was 
neither hotter nor cooler in their times than it is today. The 
fossil remains of animals and plants also tell us that the sun 
has been just about as hot as it is today for many millions 
of years. Now if the sun were a burning lump of something, 
how long would it last before it burned itself out? 

Suppose that the sun were a burning pile of wood or 
coal. A chunk of coal the size of the sun would burn for 
only a thousand years or so, if it burned fast enough to give 
off as much heat and light as the sun does. That doesn't 
come very close to the millions of years that fossil evi- 
dence shows that the sun has been shining as it does today. 

A Contracting Sun 

By the 1 800s. the idea of burning stars had been given 
up. In the I 850s, two scientists came up with an idea that 
did not use fire at all. They were the British scientist Lord 
Kelvin and the German, Hermann von Helmholtz. They 
said that the sun produces its energy by contracting, or by 

XATl'Rh AND S( II \< i 



packing the material it is made of tighter and tighter 
around the core region, or center part. (You make a snow- 
ball contract when you pack it. But you cannot pack a 
snowball tight enough to make it heat up so that it shines 
like a star.) 

Try to picture a star that is contracting. First of all, there 
is more material packed into the core region of the star 
than there is in its outer region (see Diagram A ). The mate- 
rial in each of these regions is "pulled" toward the material 
in the other region by the force we call gravitational attrac- 
tion. But the core region material wins this "tug-of-war," 
because there is more of it. The result is that atoms of the 
material in the outer region keep falling inward toward 




According to the "contracting star" theory, the greater mass 
of material in the core region of a star pulls material from 
the outer region toward the core, packing the core material 
more tightly and giving off heat and light. 

the core region (see Diagram B). Gradually the material 
around and in the core gets packed tighter and tighter. 

That is pretty much the situation that Kelvin and Helm- 
holtz imagined. Year by year, century by century, the sun 
was gradually contracting— and, as a result, heating up. 
That is what enabled our local star to pour out huge 
amounts of heat and light— or so the two scientists thought. 
But eventually this idea, too, had to be given up. Here's 
why: 

We can figure out the total amount of energy given off 
by the sun during one second, a minute, or a century. We 
can also figure out how much the sun would have to con- 




tract to produce each of those amounts of energy. It turns 
out that in one year the sun would have to contract hardly 
at all to keep shining the way it does now. Its diameter 
would become smaller by only 50 yards or so. But over 
hundreds of millions of years, the change in diameter 
would be very large. 

For the sun to have kept shining over the ages by con- 
tracting, only 100 million years ago it would have been 
more than three times as large as it is today. That would 
suggest that it was sending out much more heat and light 
and other kinds of radiation at that time than it is today. 
There would have been too much radiation reaching the 
earth for certain animals and plants to have existed. 

The fossil remains of such animals and plants, however, 
suggest that the size of the sun has changed hardly at all 
over the past 500 million years or more. Today, last year, 
a million years ago, a billion years ago, the sun cannot have 
been shining simply by contracting. But that does not mean 
that it never has produced energy by contracting. From 
what we know today, it seems certain that the sun and other 
stars do spend at least part of their "lives" shining by con- 
traction. But they do not spend the "active" part of their 
lives shining that way. 

Power Plant for a Star 

In the 1930s, scientists thought of a "model" for a power 
plant that would make the sun— or most other stars— pour 
out the same amount of energy century after century, and 
without changing in size. This model still fits well with what 
astronomers are finding out about the stars. The model de- 
pends, first of all, on the way we now think that a star is 
formed. 

In many parts of our galaxy— the vast collection of stars 
in which our Solar System is located— we see huge clouds 
of gas and "dust" (see photo). The gas is hydrogen. We are 
not sure what the "dust" is made of. 

(Continued on page 10) 



This photo shows part of the 
Milky Way, the galaxy in which 
our Solar System is located. 
The dark bands running 
through the galaxy are clouds 
of gas and dust that block 
from our view many more of 
the stars in the galaxy. 



March 3, 1969 



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Private Life of a Star (continued from page 7) 

The spiral arms of many other galaxies also have a lot 
of gas and dust (see photo). Sometimes, gas and dust are 
arranged in great patches, which we call nebulae (see photo 
on page 6). The gas and dust making up a cloud gather in 
more and more material by gravitational attraction. Even- 
tually, the cloud becomes very dense (see "How Dense Are 
You?", N&S, September 30, 1968), and it begins to take on 
the shape of a sphere. This is the first stage in the birth of 
a star, but it is not a shining star yet. At this stage, we call 
it a globule. 

From Globule to Protostar 

A globule becomes larger and larger by drawing more 
and more gas and dust into itself from the surrounding 
nebula-cloud. As more and more material falls into the 
core region of the globule, that part of the globule begins 
to heat up. It heats up because the atoms of gas and the 
particles of dust are packing themselves tighter and tighter 
together. This is just what Kelvin and Helmholtz had 
suggested. 

The tighter the packing, the more often the hydrogen 
atoms and dust molecules collide and the harder they ram 
into each other. This repeated ramming of particles pro- 
duces energy in the form of heat and light, and the globule 
begins to glow dimly. It is now what astronomers call a 
protostar— a star that is in its first stage of shining. 

In this stage, the star is shining by contracting. Material 
from near the surface of the star tumbles in toward the core 
region. As it does, the protostar gets hotter, and smaller. 

A hydrogen atom has a nucleus, or center part, with one 
tiny particle called an electron moving around it. After a 
while, the hydrogen atoms in the core region of a protostar 
are ramming into each other so hard that their electrons 
are knocked free. This leaves the electron and nucleus of 
an atom free to fly about on their own. Eventually, the 
hydrogen nuclei in the core of the protostar are packed so 
tightly together, and are ramming each other so hard, that 
they begin to lock together, or fuse with each other. 

From Protostar to Star 

When hydrogen nuclei fuse, they form the nucleus of an 
atom of a heavier gas, helium. In the process, heat, light, 
ultraviolet, x-ray, and other kinds of energy are given off. 
Matter (hydrogen nuclei) is being changed into energy 
(light, for example). The star is no longer shining by con- 
tracting. It is shining because the hydrogen nuclei in its 
core are fusing. Each second, countless billions of hydro- 
gen nuclei are fusing into helium, and releasing the heat 
energy and light energy that we feel and see from earth. 
The protostar has become a star. It has entered its active 
life, the period in which it is shining by fusing hydrogen 
in its core region. 

10 




The "arms" of spiral galaxies such as the Milky Way and 
NGC 5457 (shown here) are made up mostly of new stars 
and clouds of gas and dust from which new stars are formed. 

How long can the sun and other stars keep shining in 
this way? Since they keep using up their hydrogen fuel, 
there must come a time when there is hardly any hydrogen 
left in the core region. 

Scientists have figured out that the total amount of 
hydrogen fuel that the sun can use for fusion in the core 
region is about 3,100,000,000,000,000.000,000,000,000 
pounds. And the sun is using up its fuel supply at the 
rate of about 310,000,000,000,000,000 pounds per year. 

If we divide the smaller number into the larger one, like 
this: 

3.100,000,000,000, 
310,^ 

we find that the sun's total active life is about 10 billion 
(10,000,000,000) years. 

Astronomers believe that the earth and other planets 
of the Solar System were formed about the same time as 
the sun, out of the same mass of gas and dust. Measure- 
ments of the age of the earth's rocks suggest that this hap- 
pened about 5 billion years ago. So the sun is a middle- 
aged star with about 5 billion years more to go in its active 
life. 

As the diagrams on pages 8 and 9 show, the length of a 
star's active life depends on the amount of gas and dust that 
form a star in the first place. Because big stars have very 
high core temperatures, they use up their hydrogen fuel 
much more quickly than medium-sized and small stars do. 

NATURE AND SCll \< / 



J 



So the active lives of big stars are much shorter than the 
active lives of stars like the sun, and smaller stars. 

Red Giants and White Dwarfs 

Big, medium-sized, or small— most stars seem to go 
through a period of "old age" as red giants and end their 
lives as white dwarfs. 

When a star begins to use up the last of its core hydro- 
gen, it is ending its "active" life. Earlier, the outpouring of 
light, heat, and other energy from the core kept the star 
from collapsing in on itself. But now, with the core hy- 
drogen nearly gone, there is less energy flowing outward 
from the core. 

The star begins to "cave in" on itself, heating up again 
and drawing more and more hydrogen into the core from 
the outer region. As this hydrogen— additional fuel— is 
fused into helium, more heat reaches the outer region of the 
star than ever before. So the outer region begins to swell 
up, even while the core is shrinking. 

Over a few million years or so the star may grow thou- 
sands of times bigger. This makes it shine brighter. But its 
surface has grown so much in area that the amount of 
energy sent out from each point on the surface is less than 
before. So the star shines with a cooler, redder light. It has 
become a red giant, like the star Betelgeuse in the constel- 
lation Orion (see photo and diagram). The star continues 
enlarging and getting redder until the shrinking core be- 
comes hot enough to make helium nuclei fuse and form the 
nuclei of heavier atoms, such as carbon. 

Astronomers aren't sure what happens next, though they 
can make a pretty good guess. They think the helium fuel 
must also get used up eventually, as do a few other kinds 



of atoms that also fuse and help keep the star shining. Once 
again, the star collapses. But this time there is no swelling 
up afterwards. As its matter tumbles in toward the core 
region, the star packs itself tighter and tighter, becoming 
smaller and smaller. It is now a dwarf star and its surface 
glows white-hot. But with its fuel for fusion all used up, the 
star gradually gets dimmer and dimmer as it slowly cools. 
Eventually, after many more millions of years, the star 
probably becomes a cold, dark, extremely dense, burned- 
out star that might best be called a "black dwarf" ■ 



wn as the Pleiades a 
.y leftover gas and dust, 
are blue giants (see diagram on page 8). 




Betelgeuse, in the familiar 
constellation of Orion, is a red 
giant star. Because its sur- 
face is thousands of times 
bigger than the sun's, it 
shines thousands of times 
brighter, but with a cooler, 
redder light. 



March 3, 1969 




$b. 



■ A whiff of catnip makes a cat lively and excited. Exactly 
why catnip has this effect on a cat is still a mystery. But 
another catnip question is closer to being answered. 

What good is catnip for the plant that produces it? This 
question puzzled Dr. Thomas Eisner, a biologist at Cornell 
University, in Ithaca, New York. Catnip is actually a chem- 
ical found in the leaves of certain mint plants. "Surely," 
said Dr. Eisner, "a mint plant gains nothing from being 
able to excite cats." He wondered why the mint plants 
make catnip in the first place. 

Scientists have been able to separate the catnip chem- 
ical, called nepetalactone, from the other substances in mint 
leaves. Chemicals similar to nepetalactone are made by 
insects. The chemicals help the insects defend themselves 
against their enemies, including other insects. So Dr. Eisner 

■ 




Looking for insect food, ants swarmed around the dead 
cockroach on the left but avoided the cockroach on the right, 
which had a. drop of the catnip chemical on it. 

12 



decided to investigate the effect of the chemical on insects. 

Chasing Insects with Catnip 

He filled a small tube with nepetalactone and held it near 
different kinds of insects. Most kinds, including spittlebugs 
and several species of beetles, tried to get away from the 
tube. Some flew away. Others turned and walked away. Dr. 
Eisner found that he could move them in any direction he 
wanted by "chasing" them with the tube. It wasn't the 
tube itself that they were trying to avoid, for they did not 
respond to the tube when it was filled with water. The in- 
sects were avoiding the catnip smell that came from the 
tube. 

With a glass rod dipped in nepetalactone, Dr. Eisner 
drew a circle around a group of ants. The insects stayed 
inside the circle; they would not cross the ring of nepeta- 
lactone. Another time, he put a drop of the catnip chemical 
in front of a group of ants that were marching toward some 
food. The ants immediately halted— and then made their 
way around the drop. 

Dr. Eisner placed two dead cockroaches near a colony 
of ants. The ants belonged to a species that sometimes uses 
dead insects for food. A little nepetalactone was dropped 
on one roach, and none on the other. Within minutes, the 
one without the chemical was swarming with ants. Few 
ants went near the other cockroach (see photo). 

These experiments showed that many kinds of insects 
avoid the catnip chemical. Dr. Eisner believes that catnip 
plants are protected from plant-eating insects because the 
nepetalactone keeps the insects away. 

Over many thousands of years, these plants have 
changed in ways that help them to survive insect attacks. 
Some other kinds of plants produce chemicals similar to 
nepetalactone. Scientists are now searching for ways to use 
such chemicals to help protect food plants from insect 
pests.— Susan J. Wernert 

\ Ml !<l AM) SCI1 \< / 




WHAT'S 
NEW 



by 

B. J. Menges 



The earth wobbles as it spins 
through space. Scientists have long been 
aware of this, but they've been puzzled 
t about what causes the wobble. The cause 
must be a continuing one. Otherwise the 
wobble would gradually get smaller and 
disappear. 

Now, two scientists believe they've 
found the cause. In a study of the earth's 
wobbling motion over a 10-year period, 
Drs. Lula Mansinha and Douglas Smylie 
of the University of Western Ontario, in 
Canada, noticed that the wobble seemed 
to follow a pattern. It would decrease 
slowly for a while, then suddenly in- 
crease. Each increase, they found, 
happened at the same time as a major 
earthquake. They now believe that earth- 
quakes may jolt the earth enough to 
cause it to wobble. 

A tiny space engine has been de- 
veloped by the National Aeronautics and 
Space Administration. It is a one-foot- 
long electric engine that produces a 
thrust, or push, of only 20 millionths of 
a pound. In comparison, each of the five 
engines used in the lift-off of the Saturn 
5 lunar rocket produces a thrust of 1.5 
million pounds. 

The weakness of the new engine isn't 
a drawback, though. Its tiny thrust is 
just what is needed to help keep com- 
munications and navigation satellites on 
course. These satellites complete one or- 
bit in the same time that the earth com- 
pletes one rotation. Thus they should 
always remain over the same spot on 
earth. But because of slight variations in 
the force of gravity, these satellites tend 
to drift from their positions. Only a slight 
push is needed to keep them from doing 
so, and this push can be provided by the 
little rocket engine. A tenth of a pound of 
fuel will be enough to keep a satellite 
where it belongs for more than three 
years. 

March 3, 1969 



Wolves are back in Yellowstone 
National Park. Rare in the United States, 
wolves seemed to have disappeared en- 
tirely from the huge Wyoming park. But 
recently six wolves have been seen there. 




All wildlife is protected in the park. 
The wolves are welcome because they 
can help control the numbers of some 
large animals there. Elk herds in the 
park, for example, have become so big 
that there is not enough food for them. 
Since wolves hunt and eat elk, they are 
expected to help reduce the size of the 
herds. 

The Loch Ness monster is making 
news again. For hundreds of years, peo- 
ple have reported seeing a large, strange 
creature in Loch Ness, a big, deep lake in 
Scotland. Now a team of scientists from 
the University of Birmingham, in Eng- 
land, has found evidence that there may 
indeed be something unusual in the lake. 

The scientists explored the depths of 
Loch Ness with sonar equipment, which 
detects underwater objects by the sound 
waves they reflect. Sonar echoes detected 
three large moving objects that an engi- 
neer with the team said were "clearly" 
animals. One object seemed to be several 
yards long, and moved through the water 
at speeds up to 17 miles per hour. It 
dove at the rate of 450 feet per minute, 
a speed that "makes it seem unlikely" 
that it was a fish, according to one of the 
scientists. The men hope to investigate 
further to see whether the Loch Ness 
"monster" can be identified. 

As people grow old, they often 
lose sight in an eye because the lens of 
the eye becomes cloudy. This condition 
is called a cataract. The only known cure 
is to remove the lens. In the standard 
operation, a surgeon simply cuts out the 
lens. The resulting wound is uncomfort- 
able and takes about a month to heal. 
But now Dr. Charles D. Kelman, a New 
York City surgeon, has found a way to 
remove the lens with "silent sound." The 
sound is "silent" because it has a higher 
pitch than human ears can hear. 



Dr. Kelman first inserts a hollow 
needle into the cloudy lens. Then the 
needle is made to vibrate 40,000 times 
per second. This produces sound waves 
that shatter the lens into pieces. The 
pieces are then sucked out of the eye 
through the hollow needle. Because the 
needle makes only a tiny wound, the eye 
heals in a few days. 

The newest threat to our rivers and 
lakes is heat. Sewage and chemicals are 
already polluting many of our bodies of 
water. Now heat is a problem, largely 
because of the rapid increase in the num- 
ber and size of electric power plants. 

Most of these plants use enormous 
amounts of water from nearby rivers or 
lakes for their cooling systems. The water 
takes up heat, and is returned to the river 
or lake 10 to 20 degrees hotter than be- 
fore. This gradually raises the tempera- 
ture of the whole body of water, causing 
some kinds of plants and fish to die. As 
more electricity is needed, this "thermal 
pollution" is bound to get worse — unless 
the water used in power plants is cooled 
before it is returned to the rivers and 
lakes. 




This photo, taken from an airplane by a 
camera fitted with infrared film, shows a 
small temperature difference between 
the Sacramento River (left) and the 
warmer American River that joins it. 
(Warm objects show up lighter than cooler 
objects on infrared film.) This kind of 
photography can be used to detect ther- 
mal pollution in waterways. (See "The 
newest threat," on this page.) 

13 



By counting and banding birds, and 
by studying their ways of nesting, 
I helped solve some of the . . . 

Secrets of 



Kure Island 








by Alan H. Anderson, Jr. 




14 



■ For 10 weeks I joined other biologists who were study- 
ing the life of Kure Island, a small island 1,200 miles 
northwest of Honolulu. We had a small lab building be- 
hind the United States Coast Guard station. There I 
learned more about the investigations that were being done 
on the island, and the kinds of questions the other biolo- 
gists had been trying to answer. 

For example, how many birds were living on the island, 
and how did their numbers change? There is no magic way 
to answer this question. We used a very old technique: 
counting. We spent one day a week counting all the birds 



This aerial view of Kure Island shows the 
buildings of the Coast Guard station, the runway, 
and the dark Scaevola bushes that cover most of 
the mile-and-a-half-long island. 

NATURE AND SCIENCE 



on the island, species by species. A small motorcycle 
helped the work around the airplane runway, but the rest 
of the island was covered on foot, including a three-mile 
walk around the beach. The total count made in the day- 
time was low, since most of the birds are on the island only 
at night. And the birds that "use" the island are not all 
there at the same time, so the exact numbers could not be 
known by this method. 

We also wanted to find out where the birds went when 
they were not on the island. We did this by banding as 
many birds as possible. We looped an aluminum band 
with a code number around each bird's leg. Then the num- 
ber was recorded in a book, along with the date and place. 

When a banded bird is recovered— either dead or alive— 





The boobies lay two eggs 
but raise only one chick 
(above). The author put 
numbered bands on the 
legs of boobies (left) 
and other birds, to 
learn more about 
their travels. 



by someone in another place, we can learn something 
about its travels by using its band number to find when and 
where it was banded. Banding has told us, for example, 
that the young Kure albatross, which leave the island soon 
after they can fly, spend three or four years at sea before 
they return to the tiny island and breed for the first time. 
We spent many hours of the day and night banding thou- 

March 3, 1969 



sands of birds to get information such as this. 

When the Birds Return 

A problem I worked on for part of my stay was the daily 
movements of nesting blue-faced boobies. We wondered 
how long birds were away from their nests while their 
mates cared for the egg or chick. How long did one bird of 
a pair sit on the nest before being relieved by its mate? I 
spray-painted some dots on the upper breasts of several 
nesting birds so that I could recognize the individual birds. 
Then, beginning at one o'clock one morning, I checked 
each nest hourly to see if and when the birds on nests had 
been relieved by their mates. 

I found that all of the birds came back to the island 
around dusk to spend the night. Shortly after sunset, clouds 
of shearwaters, petrels, and terns swarmed offshore like 
airplanes waiting to land at a crowded airport. 

The boobies usually landed in the same spot night after 
night. The incoming bird would spot its nest from afar; 
the female would give a honk to identify herself, and the 
male would answer with a call like a wheeze. They would 
greet each other with calls, gestures, and bill-touchings as 
though they had been separated for years rather than 
hours. 

I discovered that most of the boobies seldom sat on 
their nests for more than 1 2 hours at a stretch. Those that 
kept long or irregular hours turned out later to be poor 
parents whose eggs might not hatch. One bird sat on her 
eggs for four days; even then she was relieved only for a 
few hours. As I expected, she and her mate failed to raise 
a chick. 

An Extra Egg 

During my visits with the boobies I noticed that they 
lay two eggs but raise only one chick. With this system, 
there is a "back-up" egg in case one fails to hatch. Several 
times, when it seemed that neither egg would hatch, I re- 
placed one with an extra egg from another nest. Each time, 
the foster parent accepted it. 

When the time came for me to leave Kure, conditions 
had changed a great deal since that foggy afternoon when I 
saw the island for the first time. The days were now warm 
and sunny. Several dozen seal pups paddled around the 
lagoon in their first tries at swimming. The largest booby 
chicks— helpless white balls of fluff that were constantly 
stuffed with fish— weighed even more than their parents. 

I had learned something of how creatures "earn a living" 
on a Pacific atoll. But most of all I had seen how wrong it 
had been for a scientist to say, in 1881, that everything 
that needed to be known about islands was already known. 
Very likely there will always be new puzzles on islands for 
a biologist to solve ■ 

15 



A SCIENCE MYSTERY 




Help Cause 




■ "Don't stay out in the snow too long— you'll get a chill 
and catch cold!" That's what mothers always seem to be 
saying. But does getting a chill or staying out in the cold for 
a long time really make you catch cold? 

Scientists have known for a long time that colds are 
caused by viruses— tiny particles of matter that can invade 
your body cells and make the cells produce many more 
viruses of the same kind. When a cold virus gets into the 
surface cells in your nose or throat, the cells also produce 
more of the mucous fluid that makes you cough or blow 
your nose so often. 

Viruses alone aren't enough to explain a cold, though. 
There are usually many viruses inside your nose that could 
give you a cold, and yet you don't have a cold all the time. 
Since most colds occur in winter, many people believe 
that cold weather must have something to do with it. 

Does a Chill Make You III? 

Recently, Dr. R. Gordon Douglas, of Baylor University 
College of Medicine, in Houston, Texas, did some experi- 

16 



ments to see whether cold or chilling seemed to help viruses 
cause colds. Dr. Douglas and his co-workers exposed some 
healthy men to cold and damp, some to cold viruses, and 
some to both. No colds developed in the men who had been 
exposed to cold and damp but not to cold viruses. What's 
more, the men who had been exposed to cold, damp, and 
viruses caught no more colds than the men who had been 
exposed to viruses alone. And the colds were no worse for 
one group than for the other. 

This seemed to show that cold and chilling don't increase 
a person's chances of catching cold, or of having a worse 
cold than he would without having been cold or chilled. 
Why, then, do most colds occur in winter? The scientists 
at Baylor University suggested that it may be because in 
winter people tend to crowd together indoors, where cold 
viruses can be easily spread by a cough or sneeze. Also, 
since viruses are only active when they are in contact with 
living things, it may be easier for a virus to survive under 
these conditions. A virus wouldn't have as far to travel 
between people in, say, a movie theater, as between people 
in a park. 

Warm Rooms and Cold Viruses 

Another possibility is that going from warm to cold 
places and back again may help cause people to catch cold. 
Most people going to work or to school in winter start out 
from a warm home, go out into the cold, and then go into 
a warm office, factory, or school. If they have to ride in a 
car, bus, or train, they will go through still another warm- 
cold change before they get to where they're going. Pos- 
sibly these rapid changes in temperature reduce a person's 
resistance to colds. 

Another idea is that winter heat may help cause colds. 
The heating systems used in many homes and other build- 
ings tend to reduce the humidity, or amount of moisture 
in the air. Low humidity can "dry out" the sensitive lining 
of your nose, which helps protect you against cold viruses. 
When this happens, the lining may be less able to keep the 
cold viruses from getting past it. 

Any or all of these ideas may help explain why people 
get their colds mainly in winter. Or there may be some 
other explanation that no one has thought of yet. Some 
scientists think that when a person has just caught cold, 
but before he is aware of it, he becomes more sensitive to 
low temperatures and chills. If he feels cold or chilled 
before he begins coughing or sneezing, he is likely to feel 
that the chill brought on his cold, rather than that his cold 
made him feel chilly. This can explain why a person thinks 
the cold weather made him catch cold, but it still doesn't 
explain how he caught the cold. 

For that answer, we will just have to wait— handkerchief 
in hand.-R. J. Lefkowitz 

NATURE AND SCIENCE 



Using This Issue . . . 

(continued from page 2T) 

The Catnip Chemical 

Your pupils may want to know what 
happens to cats when they sniff catnip. 
Fresh, fragrant catnip will not affect all 
cats, because the ability to respond to 
the catnip chemical is inherited. When 
it does have an effect, the cat responds 
by head-first rolling and face-rubbing. 
This behavior is similar to that of a 
female cat "in heat," the period when 
she is sexually excited. So some scien- 
tists believe that nepetalactone smells 
like a chemical normally produced by 
cats at the beginning of courtship. 

• To a person who doesn't under- 
stand how scientists work, the question 
—What good is catnip for the plant that 
produces it? — might seem "silly," or 
"not worth wasting time on." But all 
new knowledge is obtained by testing 
what we already know in new situa- 
tions. In Dr. Eisner's question, the 
part we already know is that some 
plants produce chemicals that repel in- 
sects or other animals that might eat 
the plants. 

In addition, Dr. Eisner had some 
knowledge that is not implied in the 
question. He knew that scientists have 
recently found that some insects make 
chemicals similar to the catnip chem- 
ical and use them to repel other kinds 
of insects that attack them. This sug- 
gested that the catnip chemical might 
protect the mint plant from insects that 
would otherwise endanger its survival. 
These facts make it easier to under- 
stand why Dr. Eisner asked the ques- 
tion he did and sought the answer by 
testing the catnip chemical on insects. 
While he did not start out to find a new 
substance that would protect plants 
against insects without harming either 
the plants or the insects, it is conceiv- 
able that the catnip chemical, and simi- 
lar chemicals produced by other plants, 
might be used for that purpose. 

• Have your pupils think of other 
ways that plants have become adapted 
for survival in their environments. For 
example, thick skin and sharp spines 
help protect certain species of cactus 
from being eaten by animals. Some 
plants trap and digest insects that pro- 
vide minerals needed for growth. 

March 3, J 969 



Others have colors, odors, and food 
substances that attract insects, which 
spread pollen from plant to plant, en- 
abling the plants to reproduce. 



Brain-Boosters 

Mystery Photo. The lopsided pine 
tree is near the ocean. Strong winds 
blowing from the sea prevent the tree 
from growing normally. 

A tree growing at the borderline be- 
tween a field and a forest may also 
grow in this way. The greater amount 
of sunlight reaching the tree across the 
open field causes more branches to 
grow on the field side of the tree than 
on the forest side. Can your pupils find 
any such trees in their neighborhood? 

What will happen if? The wax drop 
at end B of each aluminum foil strip 
should melt first, since more heat can 
flow through the wide part of each 
strip than through the narrower part. 
If your pupils perform this investiga- 
tion in class, be sure that they attach 
the sticky-tape "handles" to the alumi- 
num strips, to avoid burning their fin- 
gers. 

You might encourage the class to 
try the investigation with aluminum 
strips of different lengths, widths, or 
shapes. 

Can you do it? To make ice cubes of 
three different colors, first color some 
water with food coloring, fill the bot- 
tom third of an ice tray with it, and 
freeze it in the school refrigerator. 
Then add a second layer of different- 
colored water. When the second layer 
is frozen, add a layer of a third color. 

Challenge your pupils to try making 
other kinds of unusual ice cubes at 
home. Can they make a round ice 
"cube," a hollow ice cube, an ice cube 
with a pebble inside, or a milk or soda 
pop "ice" cube? 

For science experts only. When it 
rained, raindrops collected on the 
helium-filled balloon. The weight of 
the water made the balloon fall to the 
ground. 

If you or a pupil can bring a helium- 
filled balloon to school, the class can 
experiment with it to find out how 
much weight it can hold up. How many 
paper clips can they attach to the bal- 
loon's string before the balloon sinks 



to the floor? Will the balloon hold up 
more paper clips in the cold air out- 
doors, or in the warm classroom air? 

Just for fun. Have some pupils 
bring in some barren soil from out- 
doors, and set it on a windowsill in a 
flowerpot, pie tin, or other container. 
Assign some pupils to keep the soil 
watered and make observations daily. 
Can your pupils identify whatever may 
grow in the soil? If nothing grows, do 
your pupils think that this means that 
there is nothing in the soil that can 
grow? Or can there be some other ex- 
planation for why nothing is growing? 

Fun with numbers and shapes. The 
diagrams show three different ways for 
the people in the little houses to build 
a fence that will allow them access to 
the lake while keeping out the people 
in the big houses. Can your pupils fig- 
ure out which would be the cheapest 
fence to build? (If they measure the 
three fences with a length of string, 
they will see that fence A is the shortest 
and would require the least amount of 
fencing materials. ) 




Putting Our Hows and Whats . . . 

(continued from page 1 T) 

element, the spectroscope reveals an 
emission-line spectrum. When the ele- 
ment is vaporized, its atoms become 
part of the hot gas of the flame and 
radiate light of certain wavelengths 
characteristic of that element. Each 
element has its own set of wavelength 
"fingerprints" (see diagram). This 

HYDROQEN 

mwmwmm\ 

HELIUM 

miiiiinH 

LITHIUM 




IRON 

IIIIIIIIIIB 

GOLD 



Each element has its own characteristic 
pattern of spectrum lines, bright or dark 
depending on whether the vaporized ele- 
ment is emitting or absorbing light at 
those same wavelengths. 

property of atoms is an invaluable aid 
to the astronomer. It enables him to 
identify the gases making up stars (and 
the atmospheres of the planets). 

It so happens that atoms can absorb 
the same wavelengths of light that they 
radiate. If you vaporized some sodium 
in a flame you would see a single bright 
(emission) line against the continuous 
spectrum of the flame. Now suppose 
that you take the sodium out of the 
flame. Also suppose that there is now 
a thin cloud of sodium gas between 
your spectroscope and the flame. The 
sodium atoms of that cloud absorb the 
light of their characteristic wavelengths 
being radiated by the flame. So, instead 
of seeing a bright (emission) line, you 
see a dark absorption line spectrum. 

Spectroscopes have enabled us to 
work out the chemical composition of 
the sun. and of other stars. The sun's 
surface radiation produces a continu- 



ous spectrum. But the gases in the sun's 
atmosphere produce an absorption 
line spectrum. So far, we have ob- 
served in the sun's atmosphere absorp- 
tion line patterns of about two-thirds 
of the hundred or so elements. By far, 
most of the atoms identified are hydro- 
gen, with the rest being mostly helium. 
In far lesser amounts, next come oxy- 
gen, followed by nitrogen, carbon, and 
neon. 

Unfortunately, we cannot see 
through the bright surface of the sun to 
find out what is inside, not even with 
spectroscopes. However, we have very 
good reasons to suppose that the sur- 
face and atmospheric gases of the sun 



are a reliable sample of the remaining 
solar matter. Hydrogen, then, seems to 
make up the bulk of the sun, and of the 
other stars. 

But what about matter spread out 
between the stars? In the early 1950s 
astronomers made a major discovery— 
an emission line in the radio region of 
the spectrum at the 21 -centimeter 
wavelength position. Hydrogen radi- 
ates radio waves of that length. Using 
radio telescopes tuned to the 21 -cm 
wavelength, a survey of space between 
the stars in our galaxy has been under- 
way for about 15 years. It turns out 
that by far most of the gas in space is 
hydrogen- perhaps 9 out of 10 atoms ■ 



A GLOSSARY OF TERMS 



Apparent brightness: The brightness a 
star appears to have as we view it from a 
distance. (See also Luminosity.) 

Constellation: The grouping of certain 
stars. The ancients recognized the groups 
as human and animal figures, for exam- 
ple, Orion,"the Hunter." By international 
agreement, 88 constellations are recog- 
nized. Because the stars are in motion 
relative to each other, the shape of each 
constellation is slowly changing. 

Galaxy: A huge system of stars. The 
galaxy of which the sun is a member has 
the shape of a flattened disk with a cen- 
tral bulge. It contains about 100 billion 
stars and has a diameter about 100,000 
light-years (see below). In addition to its 
stars, our galaxy also contains vast clouds 
of dust and gas, out of which new stars 
are being formed. Our galaxy rotates like 
a great pinwheel, different parts of it ro- 
tating at different speeds. The part con- 
taining the sun takes about 230 million 
years to complete one rotation. The sun 
lies close to the galaxy's central plane 
and about 30,000 light-years from the 
central hub, which is about 10,000 light- 
years thick. 

Light-year: The distance light travels in 
one year, at a speed of about 186,300 
miles per second. One light-year is about 
6,000,000,000,000 miles. 

Luminosity: The total amount of energy 
emitted by a star per unit of time. (The 
sun's luminosity, for instance, is 5.6 x 
10 27 calories per minute. Betelgeuse, a 
red giant, has a luminosity 4,000 times 
that of the sun. The red dwarf star known 
as Ross 248 has a luminosity only 0.0001 
that of the sun.) (See also Apparent 
brightness.) 

Milky way: The luminous band of stars 



seen on any clear night. The effect is 
caused by our looking into our galaxy 
edge-on; we see millions of stars that ap- 
pear to be crowded together, the effect 
being a hazy belt. The term Milky Way is 
sometimes used to designate our galaxy, 
which most astronomers refer to as The 
Galaxy. 

Nebulae: All nebulae are clouds of dust 
and gas. A dark nebula blocks the light 
from a field of stars behind it, and so ap- 
pears dark by contrast with the surround- 
ing lighter sky. (The "rift," or dark band 
in the summer Milky Way is caused in 
this way.) A reflection nebula is mostly 
dust that reflects the light from nearby 
stars, so the nebula appears to glow. 
(One of the most spectacular reflection 
nebulae is the one in the Pleiades. As the 
photograph on page 1 1 shows, stars in 
the Pleiades look like street lights in the 
fog. ) An emission nebula contains much 
gas that intercepts light from nearby hot 
stars. The atoms of the gas become ex- 
cited and re-emit the energy. We then 
see the nebula glow. (One emission 
nebula is the Great Nebula in Orion, 
shown on page 6.) 

Spectroscope: An instrument that sep- 
arates light into its component colors. A 
prism or a grating may be used in a spec- 
troscope. A diffraction grating is a 
polished glass or plastic sheet with as 
many as 30,000 grooves to the inch. 
When a star's light falls on this grating. 
the light waves of different lengths are 
diffracted at different angles and so form 
a spectrum. 

Star: A hot, -glowing globe of gas, that 
shines by generating its own light. Most 
stars are very much larger than planets. 
Stars generate their energy not by chem- 
ical means, but by nuclear reactions. 



4T 



satvri i\n s< ii \( i: 



nature and science 

TEACHER'S EDITION 

VOL. 6 NO. 13 / MARCH 17, 1969 / SECTION 1 OF TWO SECTIONS 

COPYRIGHT © 1969 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 



N&S REVIEWS ► 

Recent Books on 

Anthropology and Archeology 

for Your Pupils 

by Elizabeth B. Gould 



The Early Days of Man, by Roy E. C. 

Burrell; illustrated by Tony Dyson and 
the author (McGraw-Hill, 164 pp., bib- 
liography and index, $4.95). This ex- 
cellent book about Old World prehistory 
is for the serious young reader. It is 
crammed full of information and does a 
remarkable job of summarizing and 
making comprehensible a subject of vast 
proportions. Beginning with brief men- 
tions of the appearance of life forms, 
evolution, and natural selection, it 
touches on fossil remains of early man, 
and continues with a good explanation of 
archeological techniques. Separate chap- 
ters treat the Paleolithic, Mesolithic, and 
Neolithic Ages. The second half of the 
book deals with the early civilizations in 
Mesopotamia, Egypt, and India, up to 
the appearance of writing. The mass of 
information in the book has not been 
compromised by the necessity for gen- 
eralization. The reader is constantly 
made aware of such important problems 
as man's dependence on his climate and 
the influence of geographical features on 
civilization. The text is illustrated with a 
number of good maps and line drawings. 

How the World's First Cities Began, 

by Arthur S. Gregor; illustrated by W. T. 
Mars (E. P. Dutton & Co., 62 pp., index, 
$3.75). The author of this slender 
volume is clearly an admirer of cities, 
which he calls "perhaps man's greatest 
invention." Increasing control over the 
environment is his criterion for man's 
progress. With a deprecating nod toward 
man the hunter, he eagerly recounts the 
steps in the march toward urbanization: 
agriculture, animal domestication, stor- 



EHzabeth B. Gould is a student of an- 
thropology, and the wife of Dr. Richard 
Gould, Assistant Curator of North A mer- 
ican Archeology, The American Museum 
of Natural History, New York City. 



age. Life in ancient Mesopotamia pro- 
vides a focus for a detailed examination 
of the increase in populated areas. Irriga- 
tion, metal tools, increasing trade, slave 
labor, writing — all contributed to the 
concentration of people in favorably situ- 
ated areas. In the final chapter, which 
boasts of the size of modern cities, the 
author might have done well to recon- 
sider whether city life is man's greatest 
achievement. Has man's life been truly 
enriched by the city? Or is he now a 
prisoner in an environment of his own 
making? The book is illustrated with 
rather stylized drawings. 

The Pygmies: Africans of the Congo 
Forest, by Sonia Bleeker; illustrated by 
Edith G. Singer (William Morrow, 137 
pp., index, $3.25). Sonia Bleeker's ac- 
count of the life of the Pygmies of the 
Congo's Ituri Forest portrays this 
people's dependence on and affection for 
their rain forest. Their food-gathering 
techniques and daily activities, and some 
of their beliefs and ceremonies, are de- 
scribed in careful detail. The Pygmies 
emerge as a well-regulated, perfectly 
adapted, cheerful people, whose lives 
have scarcely been touched by modern 
colonial intrusions. This book seems to 
be a simplified version of Colin Turn- 
bull's The Forest People, without his 
sense of involvement and participation. 
The book is illustrated with undistin- 
guished line drawings. 

Indian Costumes, written and illus- 
trated by Robert Hofsinde (Gray-Wolf) 
(William Morrow, 94 pp., index, $2.95). 
Clothing styles of selected North Ameri- 
can Indian tribes, mostly of the West and 
Southwest, are the subject of this book. 
The book could be very useful as a refer- 
ence, perhaps for Boy Scouts doing re- 
search for an Indian show; but its catalog 
style does not recommend it for casual 
reading. The author makes parenthetical 
(Continued on page 4T) 




IN THIS ISSUE 

(For classroom use of articles pre- 
ceded by •, see pages 2T-4T.) 

• Making Solids Disappear 

Your pupils can find out some basic 
characteristics of solutions, and you 
can help them use their findings to 
plan further investigations as scien- 
tists do. 

• It's a Bird, It's a Plane, 
It's a Sonic Boom! 

Scientists are trying to find out how 
sonic booms from supersonic trans- 
port planes will affect us. 

A Whale of a Problem 

How scientists are studying whales 
in an effort to save certain en- 
dangered species. 

The Ways of Whales 

This Wall Chart emphasizes the 
evolutionary development of whales. 

• Brain-Boosters 

The Case of the Deep-Frozen 
Grasshoppers 

Grasshoppers found frozen in a 
Montana glacier made scientists 
wonder how the insects got there, 
and why the species has vanished. 

• Dream Trees 

How scientists try to develop trees 
that grow faster and yield better 
lumber. 

IN THE NEXT ISSUE 

Special-topic issue: Life in the City 
. . . The past, present, and future of 
cities . . . How a city "creates" its 
own climate . . . Crowded people . . . 
The plants and animals that share 
our cities ... Controlling pigeon 
numbers. 






USING THIS 

ISSUE OF 

NATURE AND SCIENCE 

IN YOUR 

CLASSROOM 



Making Solids Disappear 

Investigating solutions as suggested 
in this Science Workshop article will 
stir your pupils' interest and curiosity 
about a process so common that we 
seldom think about it. You can help 
them to evaluate their findings, to de- 
velop further investigations as scien- 
tists do (see "Suggestions" below), and 
to understand why solutions are vital 
to all living things (see "Topics" be- 
low). 

Suggestions for Classroom Use 

• The investigations can be done 
in the classroom, or — even better — at 
home in the kitchen, where hot and 
cold water and the other needed ma- 
terials and equipment are handy. Have 
each pupil write a brief description of 
each investigation and his findings, 
something like this: "Poured 2 fluid 
ounces of cool water into a clean glass. 
Added 1 level teaspoonful of white 
granulated sugar to water and stirred 
about 30 seconds. Waited 30 seconds 
to see if sugar settled to bottom of 
glass. It dissolved. Washed and dried 
spoon, then added more sugar. In the 
same way, added a total of 20 tea- 



NATURE AND SCIENCE is published for The American 
Museum of Natural History by The Natural History 
Press, a division of Doubleday & Company, Inc., fort- 
nightly September, October, December through March; 
monthly November, April, May, July (special issue). 
Second Class postage paid at Garden City, N.Y. and at 
additional office. Copyright © 1969 The American 
Museum of Natural History. All Rights Reserved. Printed 
in U.S.A. Editorial Office: The American Museum of 
Natural History, Central Park West at 79th Street, 
New York, N.Y. 10024. 



SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester 
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calendar year (17 issues) $3.75, two years $6. Single 
copy 30 cents. In CANADA $1.25 per semester per 
pupil, $2.15 per school year in quantities of 10 or more 
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spoonsful of sugar to the water. Part 
of the 20th spoonful did not dissolve. 
Result: 2 fluid ounces of water dis- 
solved 19Vi teaspoonsful of sugar." 

Explain to your pupils that these de- 
scriptions are not "written homework," 
to be turned in and graded, but scienti- 
fic records for use in comparing their 
procedures and findings with those of 
others who have made the same in- 
vestigation. 

• If your pupils follow the direc- 
tions for a particular investigation 
carefully, their findings should be 
about the same. By comparing their 
records of procedure with each other, 
your pupils may be able to trace small 
differences in their findings to differ- 
ences or inaccuracies in measuring the 
amounts of solute and solvent, or to 
differences in the temperature of the 
solvent used. 

Fluid ounces should be measured 
with a standard kitchen measuring cup, 
if possible, and level teaspoonsful with 
a standard kitchen measuring spoon 
(1 level teaspoonful equals Vfe fl. oz.). 
The temperatures of the water can be 
measured with a common alcohol 
thermometer, but warn your pupils 
that the thermometer will break if 
placed in water hotter than about 1 10° 
or 1 20° Fahrenheit. 

Pupils whose findings differ widely 
from those of their classmates should 
be encouraged to compare their pro- 
cedures with those of other pupils, to 
seek an explanation for the wide dif- 
ference in their findings, and to try the 
investigation again to see whether they 
get the same results. 

If a number of pupils have inde- 
pendently made the same investiga- 
tion in the same way and their findings 
differ only slightly, the class will prob- 
ably agree that those findings can be 
taken as a useful description of the 
event they were investigating. Have 
your pupils try to make up a sentence 
that includes, or summarizes, the find- 
ings that seem most accurate. For ex- 
ample: "Two fluid ounces of 'cool' 
water will dissolve about 17 to 20 level 
teaspoonsful of white granulated 
sugar." (You might point out that 18 
level teaspoonsful equals 3 fluid 
ounces, so the water dissolved about 
IVi times its own volume of sugar.) 



This raises the question of what is 
meant by "cool" water. Since your 
pupils have found that warm water 
dissolves more sugar than cold water, 
some may wish to repeat the investi- 
gation and find out how much sugar 
can be dissolved in water at a certain 
temperature. 

The article also suggests finding out 
whether 4 ounces of water will dis- 
solve twice as much sugar as 2 ounces 
of water at the same temperature. 
From the results of this investigation 
and the ones in the paragraph above, 
your pupils may be able to expand 
their general statement to something 
like this: "Water at ...." Fahrenheit 
dissolves about .... times its own vol- 
ume of white granulated sugar." 

This, of course, raises further ques- 
tions: How much more sugar will a 
given amount of water dissolve when 
its temperature is raised, say, 10 de- 
grees F.? Will 2 ounces of distilled 
water dissolve as much sugar as 2 
ounces of faucet water at the same 
temperature? And so on. 

By ( 1 ) summarizing their findings 
from each investigation in the article, 
(2) thinking of questions raised by 
each summary or making guesses (hy- 
potheses) based on it, (3) figuring out 
ways to investigate these questions or 
guesses, and (4) revising each sum- 
mary on the basis of their findings, 
your pupils could probably go on in- 
vestigating solutions for the rest of 
their lives! And they might find the an- 
swers to some questions about solu- 
tions that scientists have not yet been 
able to answer. 

Topics for Class Discussion 

• How would you describe a solu- 
tion? From the investigations in this 
article, your pupils might describe a 
solution as a mixture of a solid sub- 
stance and a liquid, in which the parti- 
cles of the solid substance can no 
longer be seen. A re the particles of the 
solute spread out evenly in the solvent? 
By tasting samples from different parts 
of a sugar solution, your pupils can 
guess that the sugar is distributed 
evenly in the water. Are all solutions 
formed of a liquid and a solid? No. 
Liquids can dissolve solids, other liq- 
(Continued on page 3T) 



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NATURE AND S< II \( I 



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nature and science 

VOL. 6 NO. 13 / MARCH 17, 1969 
CONTENTS 

2 Making Solids Disappear, by Robert Gardner 

4 It's a bird . . . It's a plane . . . It's a sonic 
BOOM! 

6 A Whale of a Problem, by Robert Foy 

8 The Ways of Whales, by Margaret E. Bailey 

1 1 Brain-Boosters, by David Webster 

1 2 The Case of the Deep-Frozen Grasshoppers, 

by Margaret J. Anderson 

1 4 What's New?, by B. J. Menges 

15 Dream Trees, by Rod Cochran 



PICTURE CREDITS: Cover, Culver Pictures. Inc.; pp. 2-4, 11-12, 15, drawings 
by Graphic Arts Department, The American Museum of Natural History; p. 5, 
Fred E. Mang, Jr., courtesy of National Park Service; pp. 6, 7 (except top left), 
9, photos from U.S. Wildlife Service; pp. 7 (top left), 8, 10 (top), photos by 
Robert Foy; pp. 8-9, artwork by Lloyd P. Birmingham; p. 10 (bottom), photo 
from AMNH; p. II, photo by Dave Webster; p. 12, left photo by W. C. Alden, 
right photo from Union Pacific System, both courtesy National Park Service; 
p. 13. Irving Friedman, courtesy U.S. Geological Survey; p. 14, courtesy of the 
Raytheon Company; pp. 15-16, photos by Rod Cochran. 



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A spoon is not a "magic wand," 
but waving one around in the right 
place will speed up 
the process of... 




by Robert Gardn^ 

■ Have you ever watched a spoonful of sugar disappear 
a cup of hot tea? Or flavored crystals vanish as you si 
them into water to make a cool drink? When a solid d 
appears in a liquid, we say that the solid has dissolved 
the liquid. Chemists say that the solute, or solid substanc 
dissolves in the solvent, or liquid, to form a solution. 

Do all solids dissolve in water? Does the temperature • 
the water affect the amount of solid that dissolves in i 
Can you separate the solute from the solvent once it h^ 
dissolved? Will liquids other than water dissolve solid 
Does one dissolved solid interfere with the dissolving t 
another one? Here are some experiments that will help yc 
find the answers to these questions. 

Solids in Water 

Use a kitchen measuring cup to pour equal amounts <j 
water into two glasses. Two ounces (}A cup) of water 
each glass will do. Now add one level teaspoonful of sugi 
to one glass. (To get a level teaspoonful, use a card or 
ruler to sweep off all the sugar that is above the edges 
the spoon.) Stir the water until all of the sugar crystals di 
appear. Can you taste the sugar in the water? 

How much sugar will the water hold in solution? Yd 
can find out by stirring in one level teaspoonful after ai 
other until the crystals will no longer disappear in the wate 



Which will dissolve first, sug 3 
crystals packed together in 
cube or the same number o 
crystals separated by mash 
ing a cube? Add equ i 
amounts of water to eat I 
glass and do not stir. Can yoi 
explain what happens? 



NATURE AND SCIENCE 








Now dissolve a level teaspoonful of salt in the other 

ass of water. (Use kosher salt if you have it, because 

f tost other commercial salts contain added substances that 

nake the water a bit cloudy when the salt dissolves in it.) 

•!an you taste the salt in the water? Will two ounces of 

'ater dissolve as much salt as sugar? More? Less? 

When you have dissolved as much salt as possible, pour 
he solution into another glass, leaving the undissolved 
rystals behind. Do you think sugar will dissolve in this 
'alt water? Try it and see. Will salt dissolve in water that 
nas dissolved all the sugar it will hold? 
' Surely the more water you use, the more sugar or salt 
'ou can dissolve in it. Will four ounces of water dissolve 
wice as much sugar or salt as two ounces of water will? 

Try using hot water instead of cold water, and see if the 
'emperature affects the amount of sugar or salt that a cer- 
ain amount of water will dissolve. 



low To Make and Use a Filter 




— MORE INVESTIGATIONS — 

1. Will other liquids dissolve the same substances 
that water does? Try rubbing alcohol, cooking oil, and 
liquid detergent, for example. Try vinegar, too. (What 
happens when you add bicarbonate of soda to vine- 
gar?) 

2. Will water that has dissolved as much salt as it 
can hold dissolve still more salt if the water is heated? 

3. If you add three fluid ounces of sugar to three 
fluid ounces of water, will you get six fluid ounces of 
sugar water? (Use a measuring cup to find out.) Can 
you explain your findings? 





WATER 



SUGAR 



4. Dissolve as much salt as you can in a jar of 
water. Place a thermometer in the salt water, then put 
the jar into a freezer. Look at the thermometer every 
few minutes to see what happens. At what tempera- 
ture does the liquid freeze? 32° Fahrenheit? Lower? 

5. Does a level teaspoonful of sugar weigh the 
same as a level teaspoonful of salt? You have been 
measuring the volume of a solid that dissolves in a 
liquid. How could you change your measurements so 
that you could compare the weights of different solids 
that dissolve in equal volumes of water at the same 
temperature? 



You might also try to dissolve other substances in water. 
Try bicarbonate of soda (baking soda), tooth powder, 
flour, starch, instant tea or coffee. You can probably think 
of other substances to try. Does the temperature of the 
water affect the amount of these solids that dissolves? 

Separating Solids from Liquids 

Are you sure that each of the substances you stirred into 
water is dissolved? If a solid is not dissolved, but is just 
mixed with the water, you should be able to separate the 
solid from the water with a filter. You can make a filter 
with a paper towel and a funnel, as shown in the diagram. 

Try pouring the water containing the dissolved sugar or 
salt through a filter. Can you find any sugar or salt crystals 
on the filter paper? Does the water that passed through the 
filter still taste sugary or salty? Pour this water into a 
shallow dish or saucer and place it near a radiator, or in 
some other warm place, for a day or two, and see what 
happens. 

Can you separate flour from water by pouring through a 
filter? How about tooth powder and water? (Be sure to use 
a new filter for each investigation.) ■ 



March 17, 1969 



It's a bird . . . 



It's a plane... 



Passenger planes that fly faster than 
sound will BOOM, instead of ZOOM, 
past us. Scientists are trying 
to find out whether we 
will be able to take it. 



It's a sonic 




■ Have you ever heard a loud, sharp Boom! as a jet plane 
streaked across the sky above you? Perhaps not, because 
so far only military planes fly fast enough to make this 
noise, and they usually try not to make it where many 
people live. But near the bases where these planes take off 
and land, people often hear a sonic boom, as the noise is 
called. 

The boom is caused by a single "super" sound wave that 
forms around an airplane that is traveling at a supersonic 
speed— faster than sound waves travel through the air (see 
diagrams). 

The boom may startle you, but it probably won't damage 
your ears. If you are indoors, you may not hear much of 
a boom at all, but you will probably hear something else 
—the rattle of shaking walls, doors, and windows. The 
sudden change in air pressure as the giant wave passes 



the house makes walls vibrate, or shake, as a drumhead 
vibrates when you give it a hard beat. 

This vibration can break windows and cause other 
damage. The United States Air Force paid out nearly 
half a million dollars in 1967 for damage caused by sonic 
booms from its planes. In France, a sonic boom recently 
made an old farmhouse roof collapse, killing three people. 

More and Longer Booms 

Now that giant planes are being built to carry passen- 
gers at supersonic speeds, scientists are trying to find out 
how sonic boom affects people, and what— if anything— 
can be done about it. 

The new supersonic transports (SSTs) will be larger 
and will fly higher than the supersonic military planes. The 
sound of the SST's boom should last a little longer and 



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A sound wave starts, for example, when 
a firecracker explodes and compresses, 
or pushes together, the particles of air 
next to it. These particles bump into each 
other, then bounce apart, compressing 
the air particles next to them. In this way, 
the "push" from the explosion is passed 
along through the air at a speed of about 
760 miles per hour. When it reaches the 
air at your ears, it gives your eardrums a 
sudden push and you hear a BANG! 






A flying airplane is always com- 
pressing the air directly ahead of it, 
making a continuous series of 
sound waves. When the plane is 
traveling slower than sound waves 
travel through air, the waves out- 
run the plane and spread out in all 
directions as they move away from 
it. As long as these waves reach 
your ears, you hear a continuous, 
steady sound. 




When a plane is flying at supersonic speed, i 
outruns the sound waves it makes, and the 
pile up in a single wave of compressed air. This 
wave is something like the water wave tha 
forms at the bow, or front, of a speedboat. Bu 
the compressed air wave forms a giant cone ir 
the air around the plane, as shown in thi 
diagram. When the edge of this cone passe* 
you, the air in it gives your eardrums a stron§ 
push and you hear a sonic BOOM! 



Sonic booms from military planes may have caused recent 
damage to ancient dwellings such as these homes of pre- 
historic cliff dwellers at Mesa Verde National Park, in 
Colorado. Here and at other national parks, microphones 
and recorders have been set up to keep track of the number 
and strength of sonic booms reaching each area daily. 



reach people in a wider path along the ground, but it 
should be a bit softer because the plane is farther away. 
If the SSTs are used to fly people across the United States, 
scientists believe that their sonic booms may damage mil- 
lions of dollars worth of buildings and other property each 
year. And, depending on the routes these planes follow, 
people on the ground may hear from one to 50 sonic booms 
a day. 

The question is, can people get used to these noises, as 
they have to the roar of jet engines and the rumble of heavy 
trucks, for example? Or will the louder and more sudden 
booms be too much for people to stand? 

At Edwards Air Force Base, in California, scientists 
tested the effects of sonic boom on about 350 people. 
Some of them lived or worked at the base; others lived 
some distance away. All were at the base, either in houses 
or outdoors, during the tests. 

Jet planes were flown over the base, sometimes at super- 
sonic speeds so that they produced booms, and sometimes 
at slower speeds, so only the roar of their engines could be 
heard. The people were warned one minute before each 
plane came, and were asked afterwards how pleasant or 
unpleasant the sounds from the planes were to them. 

The people who lived and worked at the base had heard 
sonic booms many times before. They were much less 
bothered by the booms than the people who lived farther 
away and had not heard as many. This suggests that peo- 
ple can get used to sonic booms. Some scientists have 
pointed out, though, that the people who worked at the 
base had to "get used to" the booms if they were to keep 
working there. 

Louder and Louder Booms 

The Federal Aviation Agency conducted a test in 
Oklahoma City, Oklahoma, to find out how people might 
feel about booms from civilian planes on regularly 




scheduled flights. For about six months, a plane flew over 
the area at supersonic speed at the same times, eight times 
each day. 

For the first few weeks, the plane was flown so that its 
sonic booms got a little stronger each day. Then the booms 
were kept at the same strength for 15 weeks. Then the 
strength of the booms was stepped up even more during 
the last six weeks of the test. Early in the tests, in the 
middle, and again at the end, the people in the area were 
asked whether they thought they could "learn to live" with 
eight booms a day from passenger planes. 

At first, about four people out of five thought they could 
get used to the booms. But by the end of the tests, only 
about three people out of five felt that way. And the num- 
ber of people who said they definitely could not get used 
to the booms rose from one out of 20 to four out of 20. 
Scientists aren't sure, though, whether this means that 
people just got more irritated as the test went on, or that 
people who could stand the early booms were bothered 
more when the booms got louder. 

The results of these tests, and of others that have been 
made, do not prove that people can't live with the added 
booms that SSTs will bring. But people are beginning to 
feel that "noise pollution" is just about as bad as air and 
water pollution. Some people think that the SSTs should 
only be permitted to fly over the oceans, where their booms 
would only reach ships. Meanwhile, engineers are trying 
to find ways to soften the boom, since they probably can't 
silence it completely if we must fly faster than sound ■ 



Boom from Above, Bellows Below 



Planes booming overhead might disturb other living 
things besides humans. During the tests at Edwards Air 
Force Base in 1966, a group of high school students 
investigated how sonic booms affect farm animals. 
They watched different kinds of animals before each 
boom, at the time of each boom, and just afterwards. 



The booms didn't change the behavior of the large 
animals much. Some horses jumped up and galloped, 
some cattle bellowed, but few cows being milked even 
raised their heads. The chickens seemed more fright- 
ened, and the booms may have made other birds produce 
fewer eggs. 



Whale hunters have been so good at their job 
that some species of whale are in danger 
of dying out. Scientists are now 
studying whales to find 
out how to solve . . . 



.■^"V . 




by Robert Foy 



This scientific "gunman" aboard a whale-marking ship aims his special 
gun, ready to shoot an identifying mark into a blue whale. 



■ A blue whale may weigh as much as 25 elephants and be 
almost one-third the length of a football field. You would 
think that a creature that size could take care of itself. 
But the blue whale has been no match for the cannon- 
launched harpoons of modern whale hunters. The blue 
whale and several other of the largest kinds (species) of 
whale have been killed in such large numbers that they 
are in danger of dying out. (Before modern weapons and 
steam-powered ships, whales had at least a fighting chance. 
See cover.) 

Whales are hunted because they are useful to man in 
several ways. Whale oil is used to make margarine and 
soap. Whale meat is used for animal feed, and the rest of 
the carcass is ground up for fertilizer or poultry feed. The 
Japanese, who kill more whales than any other nation, 
consider whale meat a dinnertime treat. 

Once many whale catchers roamed the Antarctic waters 
in search of these giant mammals. But so many of the 
whales there have been killed that the hunters are now 
going to other areas, such as the North Pacific. There, 
about 19,000 whales are killed each year. This area is 
home for many of the world's largest whales, including 
the sperm whale, now the most hunted species because 
of its large supply of oil. 

Investigating Whales 

Scientists like marine biologist Dale W. Rice have found 
the North Pacific a good place to learn about whales. Rice 
works at the United States Bureau of Commercial Fish- 
eries' Marine Mammal Biological Laboratory, in Seattle, 
Washington. His job is to find out as much as he can about 



whales in the North Pacific— how many there are; their 
habits, travels, foods, diseases; and how often they repro- 
duce. 

What Rice and other United States scientists find out 
about whales is combined with information from Japan, 
Canada, and the Soviet Union. It is then studied by mem- 
bers of a scientific committee of the International Whaling 
Commission, who try to figure out what is happening to 
different whale species around the world. This information 
can be used to set limits on whale hunting so that no species 
will be killed off. 

Rice is studying seven species of whale. They include 
the blue, finback, sei. gray, and humpback species from 
the baleen whale group. Whales of the baleen group have 
no teeth. Instead, they have rows of fringed bone called 
baleen plates that hang from their upper jaws (see page 8). 
The baleen plates act like a strainer to trap millions of 
tiny sea creatures for the whale's food. 

Rice is also studying the bottlenose and sperm whale 
species. They belong to the toothed whale group, having 
teeth rather than baleen plates. There are about 80 species 
of whale, but the ones Rice is studying are those that are 
in greatest danger of being hunted to extinction. Because 
each species has different habits and characteristics, each 
species must be studied separately. 

Tales from Dead Whales 

Rice gathers information about whales in several ways. 
He examines facts from other nations about whales. Some- 
times he goes to sea to observe whales. He often goes to 
California whaling stations to examine whales killed by 

NATURE AND SCIENCE 



whalers. He tries to find out as much as possible about 
each whale. 

Some of the largest whales Rice has examined have 
been blue whales. These sometimes weigh as much as 150 
tons. They are the largest artimals that have ever lived, as 
far as scientists know. But where once there were about 
150,000 blue whales in the Antarctic waters, there are now 
fewer than 1,000. The whale catchers have done their 
job too well. 

To learn about the food whales eat, Rice examines the 
stomach contents of dead whales. Sometimes the contents 
show the remains of At;'//— small, shrimp-like creatures that 
make up a large part of the diet of some whale species. 
Some whales, Rice has found, get along on a diet of small 
fish, usually anchovies. The chief food of the deep-diving 
sperm whale is the giant squid. 

The scientists from the Seattle laboratory also try to 
determine the ages of dead whales. They count the layers 
of material in a whale tooth, just as rings are counted to 
date a tree (see "Dating the Past," N&S, September 16, 
1968). They count each tooth layer as one year (see photo). 

But scientists must use a different method to determine 
the ages of baleen whales, since they have no teeth. The 
method most frequently used is to remove a wax plug (see 
photo) from the whale's ear. Scientists count the number 
of layers, or laminations, of wax in the plug. The scientists 



This ship is a Norwegian "floating whale processing plant." 
Dead whales are pulled up the rear passageway and then 
butchered aboard the ship. 



i .. 



I 



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Scientists counted the layers in 
this four-inch wax ear plug 
(above) and in this tooth, to find 
out the ages of the whales they 
came from. The tooth has 45 
layers,and the plug has 20. 



believe that each lamination of an ear plug probably means 
a year's growth in a baleen whale, but there is no positive 
proof. So they prefer to say that a baleen whale's age is a 
certain number of laminations. For example, they might 
say that a certain whale is nine laminations old. Rice has 
found some whales that are over 60 laminations old. 

What "Bugs" a Whale? 

Rice has found that whales are usually healthy, but that 
parasites sometimes trouble them. Parasites are organisms 
that live off other plants or animals and usually harm them 
in some way. Some parasites live on a whale's skin. The 
sei whale may have parasites in its liver that sometimes 
kill the whale. 

All large whales suffer from attacks by the sea lamprey. 
The lamprey is an eel-like animal with a toothed tongue 
and 125 horny teeth that help it hold tight to a whale while 
the lamprey sucks the whale's blood. 

Rice and other scientists are especially interested in 
learning more about whale travels. "If we can learn where 
whales go and why," he explains, "we will be better able 
to decide how many of each kind can be killed each year 
without causing the species to die out." 

Some species of whale travel between summer and win- 
ter homes. Rice and other scientists have found that there 
is more whale food during the summer in the cool waters 
of the North Pacific, where some species spend the summer. 
There they are hunted by whalers. 

In winter, when food is harder to find in the northern 
seas, these whales travel to warmer waters farther south. 
There they breed, or bear their young. "Being born in 
warmer waters may give the newborn calves a better 
chance for survival," says Rice. But there is still a big 
mystery about just where the whales breed in winter. If 

(Continued on page 10) 



March 17, 1969 



nature and science 



WALL CHART 



March 17,1969 




Living in the ocean has enabled the blue whale 
to grow larger than any other animal ever has. 
Whales die of suffocation if they become 
stranded on land. Without the water toVfeef^ 
support them, their great weight presses on 
their lungs so the lungs cannot fill with air. Here 
you can see a 100-foot blue whale compared in 
size with some other mammals, including the 
smallest species of whale, about 5 feet long. 



Whales are divided into two large groups according to 
their eating "equipment"; baleen whale jaw 



WATER BRINGS IN 
SMALL ANIMALS 




—BALEEN PLATE 



^ TO 
STOMACH 



( I 



Baleen whales have rows of fringed, 
horny plates, called baleen plates, 
hanging from their upper jaws. These 
plates trap tiny sea creatures for the 
whale's food. Unborn baleen whale 
calves have tiny teeth that disappear 
before they are born. This suggests 
that baleen whales once had teeth, but 
the teeth gradually disappeared as the 
whales came to depend on smaller 
creatures for food. 

TOOTHED WHALE 



TBI© Ways! 



■ Whales are among the most mysterioi ir 
creatures in the world. Scientists hav 
only begun to study them thoroughly, an 
many things that people have believe 
about them are proving untrue. 

Perhaps the greatest mystery abc 
whales is how they came to live in til h 
water. For even though whales live amor 
fish, whales are not fish. They are man 
mals, as are horses, dogs, and human } 
Biologists believe that the ancestors 
whales lived on land, because the bodi 
of modern whales show traces of featun 
needed for land-living. The whale's a 
cestors probably had ears, four legs, an b 
hair on their bodies. But something cause 
the whale's ancestors to begin living in th 



SIDE VIEW OF WHALES AT SURFACE OF OCEAN 



BLUE WHALE 




Toothed whales use their teeth to seize food such as fish or 
other sea animals. They don't chew their food, and the teeth of 
a whale are all very much alike. (Many other mammals have dif- 
ferent kinds of teeth to use for chewing or grinding.) 





>§ Whales 



iter. Perhaps they could escape enemies 
pre; or maybe food from the water he- 
me easier for them to get than land food. 
>r whatever reasons, over millions of 
ars whales gradually changed (evolved) 
:o creatures that live entirely in the 
Iter. 

There are very few clues, such as fossils, 
how this happened. So scientists must 
idy the bodies of modern whales to try 
find out what their ancestors were like 
d how they evolved into the creatures 
i know today. In this Wall Chart you 
see some of the characteristics, de- 
loped over millions of years, that enable 
lales to survive in the water. 

— Margaret E. Bailey 



BONES OF FINGERS 



REMAINING 
HIP BONE 




Whales' bodies gradually became 
adapted for living in the water instead 
of on land. The five fingers became joined in a 
fleshy flipper for steering through water. The legs 
disappeared, leaving only small hip bones embedded in 
the whales' flesh. Whales developed flat flippers, called 
flukes, on their tails that help propel them through the 
water. Their bodies lost most of their hair and took on 
a "fish" shape, streamlined for swimming. 



FLUKES 



nales take in air through openings in the tops of 

Jeir heads, called blowholes, which are connected 

their lungs. A whale closes its blowhole before 

'.unding, or diving. Some whales can stay under 
;iter for an hour or more without surfacing for fresh 
if The air in a whale's lungs gets warm and filled 

th water vapor. When the whale surfaces and lets 

is air out through the blowhole, the air is suddenly 
joled and the water vapor changes back to a liquid, 
Tming the "cloud" that is called a spout. From 

is spout and the shape of the whale as it surfaces, 
^alers can identify different species of whale. 



J 

Ki 


^B 


Baby whales (calves) are born 
alive, like the young of most 
mammals. While the calf is de- 
veloping inside the mother 
whale, it gets food from the 
mother through the umbilical 
cord, just as human babies do. 
It takes a whale calf from 8 to 
17 months to develop in its 
mother, depending on the spe- 
cies of whale. After a calf is 
born, the mother nurses it, as 
do land-mammal mothers. This 
is how a baby gray whale looks 
after it has been growing inside 
its mother for about 2V? 
months. It is about 5 inches 
long. 


UMBILICAL"^^— 
CORD ^^ 




^^ 


^ 



A Whale of a Problem (continued from page 7) 
scientists knew the exact locations, they could go there 
to count the newborn calves. This would help them to set 
future hunting rules for each whale species. 

Tracing a Whale's Trail 

One way scientists are trying to solve the mystery of 
whale travels is by marking whales. The whale "mark" is 
a pointed, stainless-steel tube about nine inches long that 
is fired from a specially designed shotgun into the back 
muscles of the whale. The mark has a number stamped on 
it, along with the request that it be returned to the Marine 
Mammal Laboratory in Seattle when it is found, together 
with information about when and where the whale was 
located. (Japanese, Russian, and Canadian marine biol- 
ogists mark whales in a similar manner.) 

When hunters kill a marked whale and butcher it, they 
find the mark. Some marks have been recovered in good 
condition after 25 years. When a whale mark is sent to the 
Seattle laboratory, Rice checks its number with the rec- 
ords. The records contain information about each marked 
whale, including when and where the whale was marked. 

If the whale was marked in California waters and the 
mark was recovered in the far North Pacific, scientists can 
tell something about the whale's travels. Marks recovered 
in the same area from different whale species would show 
that the different species were mixing together. 

Can the Whales Be Saved? 

Since 1947 the International Whaling Commission has 
tried to save the great whales by setting limits on whaling 
catches in Antarctica. But most whale hunters have ignored 




Marine biologist Dale 
Rice loads a nine-inch 
whale mark into a spe- 
cially designed shotgun. 
Rice is a United States 
representative to the In- 
ternational Whaling Com- 
mission, which is made 
up of nations that have 
agreed to control their 
whale catches. 



the limits. Out of 12 species that could once be hunted for 
profit, only the sperm whale still exists in large numbers. 
For 1 968 and 1 969, the countries that catch whales in 
the North Atlantic and Pacific waters have agreed to con- 
trol their catches. Rice says that now more nations are 
becoming interested in whale research and in sharing in- 
formation that scientists discover about whales. But it 
may be too late to save the great whales. Only if nations 
work together to control the killing and protect the whales 
for many years will the whales survive ■ 



| For further reading about whales, see these books in your 
library or bookstore: All About Whales, by Roy Chapman An- 
drews, Random House, 1957, $2.95; In the Wake of the Whale, by 
John A. Barbour, The Macmillan Company, 1969, $3.95. 



HOW DOES A WHALE "SOUND"? 



You can find out at The American Museum 
of Natural History in New York City. This 
photo shows the unfinished 94-foot model of a 
female blue whale hanging from the ceiling of 
the new Hall of Ocean Life. The photo was taken 
before the new hall opened in February. The 
whale is shown as if it were sounding, or diving 
after it had come to the surface of the ocean to 
breathe in air. The model took 21/2 years to 
build and cost $200,000. It is made mainly of 
plastic foam and Fiberglas. The new whale will 
replace the Museum's old whale model, which 
was put on exhibit in 1908. Scientists later 
discovered that the old model was inaccurate 
because it did not "bulge" properly and its eyes 
did not stick out. The Museum is celebrating 
its 100th birthday anniversary this year. 




Mystery Photo 

Why are the letters of the road sign 
so much "heavier" in some parts than in others? 



What will happen if? 

Make two small nail holes near the bottom of a tin 
can. Hold your finger over one hole, and run water 
into the can fast enough for it to fill up and stay full, 
even though water is running out of one hole. Watch 

how far the water stream 
squirts out of the open 
hole. 

What will happen if 
you take your finger off 
the second hole while 
keeping the can filled? 
Will each stream squirt 
the same distance as 
when only one hole was 
open, or will they both 
shoot out a shorter dis- 
tance? 

E V \ 

Can you do it? 

Can you add more water to a glass that is already 
brim-full? 























«nHnoH 








■■^ ' '* 






"&&■■■}" 



Fun with numbers and shapes 

Remove 8 toothpicks so that 3 squares are left. 

Submitted by Edward Siegel, Cleveland, Ohio 




For science experts only 

Where would you end up if you kept going northwest 
as far as you could? 

Just for fun 

Put some water, dishwashing liquid, and food color- 
ing into a glass. Drop in an Alka-Seltzer tablet and 
watch what happens. 




ANSWERS TO BRAIN-BOOSTERS IN THE LAST ISSUE 



Mystery Photo: The lopsided pine tree is near the ocean. Strong 
winds blowing from the sea prevent the tree from growing 
normally. Where else might you find such a tree? 

What will happen if? The wax drop at end B of each aluminum 
foil strip should melt first. Would a wax drop on a strip of 
aluminum foil ever melt if it were a foot away from the place 
being heated? 

Can you do it? Here is how to make ice cubes of three different 
colors. Color some water with food coloring and fill the bottom 
third of an ice tray with it. When the water is frozen, add a 
second layer of different-colored water, and freeze the second 
layer. Then add a layer of a third color. 

For science experts only: When it rained, raindrops collected 
on the helium-filled balloon. The weight of the water made the 
balloon fall to the ground. 



Fun with numbers and shapes: Here are three ways to build 
a fence that will keep the people in the big houses away from 
the lake. Which way would be cheapest? 




A SCIENCE MYSTERY 



The Case of the Deep-Frozen 

Grasshoppers 



Scientists have figured out 
how thousands of "Rocky 
Mountain locusts" probably 
got trapped in a Montana gla- 
cier. But why this kind of 
grasshopper has disappeared 
is still a mystery. 

by 
Margaret J. 
- Anderson 




This photo shows the top of the front edge of Grasshopper Glacier, 
where thousands of grasshoppers like the ones shown at the 
right have been found preserved in the ice. 



■ High in the Beartooth Mountains of Montana, near the 
northeast corner of Yellowstone Park, there is a very un- 
usual glacier. The bodies of thousands of grasshoppers 
are frozen in its ice. During the warm days of summer the 
face of the glacier melts, and birds and fish can feed on 
defrosted grasshoppers. 

How did these insects get there, in a glacier 1 1,000 feet 
above sea level? How long have they been preserved in 
the ice? Have they been there for thousands, or hundreds, 
or just tens of years? And what is the name of this grass- 
hopper? These are some of the questions that entomolo- 




12 



gists, scientists who study insects, have asked about the 
Grasshopper Glacier. 

A Clue from Live Grasshoppers 

The glacier has been known for more than 70 years, but 
because it is in a hard-to-reach place, not many scientists 
have studied it. One entomologist, Dr. J. R. Parker, who 
lives in Bozeman, Montana, has made several trips up 
there. He first saw the glacier in 1918. and cut some grass- 
hoppers out of the ice. On a visit in 1931, when he was 
about a quarter of a mile from the glacier he noticed a 
smell of something rotting. When he reached the glacier 
he found piles of decaying grasshoppers, two to four feet 
deep, which had been uncovered by the melting ice. 

When Dr. Parker visited the glacier on August 1, 1949, 
to collect more specimens, he found several hundred live 
grasshoppers scattered over the snow. He knew that grass- 
hoppers could not have been living very close to the gla- 
cier, and from the way they were scattered about, he de- 
cided they must have arrived there by air. He gathered 
about 30 specimens before leaving to get down the moun- 
tain in daylight. 

A few of these specimens were of two kinds (species) of 

NATURE AND SCIENCE 



grasshopper that were common on the lower slopes of the 
Beartooth Mountains. But most of them were of a species 
called Melanopus rugglesi, which had not been seen be- 
fore in Montana or Wyoming. There were swarms of rug- 
glesi in Nevada and Oregon, though, in 1949. They had 
been seen flying near the ground and at higher altitudes 
during the month of July. Could some of them have flown 
—or been blown— several hundred miles to Grasshopper 
Glacier? 

Weather Bureau records showed that winds of 10 miles 
an hour or stronger had been blowing eastward from Ore- 
gon at altitudes of 10,000 feet and higher during the last 
few days of July, 1949. Scientists believe that these air 
currents could have carried high-flying insects from Ore- 
gon to Montana. High peaks on either side of Grasshopper 
Glacier funnel the wind across it, and the insects landed 
on the snow-covered ice, where they became too numbed 
by the cold to fly farther. 

The grasshoppers found preserved in the glacier were 
not of the same species as those found alive on the snow. 
Still, it seemed likely that all had reached the glacier in the 
same way. 

In the late 1940s, scientists had developed the carbon- 
14 method of testing the remains of plants and animals to 
find out how long ago they were alive {see "Dating the 
Past," N&S, September 16, 1968). This test was used on 
the remains of grasshoppers cut from the ice at the glacier, 
and they were found to be fairly recent— probably less than 
200 years old. 

What Happened to Melanopus spretus? 

Dr. A. B. Gurney of the United States Department of 
Agriculture studied the grasshopper remains and found 
that they belonged to a species called Melanopus spretus. 
And this brings us to a new mystery. This grasshopper is 
commonly called the "Rocky Mountain locust." A hun- 
dred years ago— from 1866 to 1877— there were tremen- 
dous swarms of these grasshoppers traveling mainly in 
areas between Canada and Texas, and from Wyoming and 
Colorado to Minnesota, Iowa, and Missouri, destroying 
farm crops and native plants wherever they went. It may 
have been during this time of dense flights that many of 
the grasshoppers were trapped in the glacier. 

Then the numbers of Rocky Mountain locusts began to 
get smaller and smaller; the last live insect of this species 
was recorded in 1 902. Just as the buffalo disappeared from 
the plains, this grasshopper vanished. Some scientists 
even wonder if it depended on the buffalo in some way. 

These scientists are boring into the base of 

an ice cliff to blast out chunks 

containing long-preserved grasshoppers. 



Perhaps the females laid their eggs in ground trampled by 
buffalo, or the young grasshoppers may have fed on dried 
buffalo manure. No one knows. 

These flights of grasshoppers in the 1 800s were nothing 
new. Since Biblical times "plagues" of grasshoppers have 
caused destruction throughout the world. Large swarms 
can block out the sunlight and turn day into "night." And 
when they land to eat, they leave the ground bare for 
miles around. The thing that puzzled scientists was that 
swarms could build up so suddenly— seemingly out of 
nowhere. 

Then Dr. B. P. Uvarov, Head of the Anti-Locust Re- 
search Centre in London, England, explained this puzzle. 
He found that the insect leads a double life. It can live 
alone, as a solitary grasshopper, or it can live and breed 
in swarms. The strange thing is that when the solitary 
hoppers in an area grow in numbers, crowding together 
makes them more active, and somehow changes their body 
processes. And these changes, in turn, cause an individual 
insect's color to darken and the sizes of its body, wings, 
and other parts to change. Not all grasshopper species 
change in this way— only a few kinds, which are often 
called locusts. 

Could the Rocky Mountain locust still be around in a 
different form, living as a solitary grasshopper? Will it 
someday swarm again? Or are the swarms trapped in the 
glacier the last examples of a vanished species? These are 
mysteries yet to be solved ■ 




March 17, 1969 



13 



WHAT'S 
NEW 





by 

B. J. Menges 



Insects that never touch land are 

being studied by scientists of the Woods 
Hole Oceanographic Institution, at 
Woods Hole, Massachusetts. These 
ocean-going insects are rare waterstriders 
called Halobates. Like the common 
waterstriders that you may have seen 
scurrying across the surface of ponds 
{see " 'Surfing' to Safety," N&S, October 
14, 1968), the ocean-dwelling water- 
strider is covered with water-repellent 
hairs and has six legs, two of which act 
as oars. With its sharp mouth, it pierces 
jellyfish and other marine animals and 
feeds on their body fluids. 

These half-inch-long insects have al- 
ways been hard to study. They spend 
their entire lives hundreds of miles from 
shore and move very fast. Recently, 
though, scientists invented a new kind of 
net that skims the striders off the ocean 
surface so they can be taken aboard a 
ship for study. But one problem remains. 
The striders move so fast that when they 
are put into an aquarium, they bump 
into the glass and kill themselves. 

With no water to drink, an ante- 
lope called the oryx thrives in the hot 
deserts of Africa. Some small desert ani- 
mals can also live without drinking. 
Some of them eat plants or other animals 
that contain water. Others can "manu- 
facture" water in their own bodies, and 
they spend hot days in cool underground 
burrows. But the oryx does none of these 
things. Where does it get water? And 
how does it keep from overheating in the 
hot sun, or losing too much water by 
evaporation through its skin? 

To answer these questions, Dr. C. R. 
Taylor, a zoologist at Duke University, 
in Durham, North Carolina, ran tests in 
a laboratory under desert conditions. At 
night, he reports in Scientific American, 
the usually dry desert grasses that the 




This miniature furnace (arrow) is no big- 
ger than a two-pound coffee can, but it 
could still heat a nine-room house. The 
new furnace, developed by the Raytheon 
Company, of Lexington, Massachusetts, 
could use gas or other fuels to heat water 
or air in a home or factory, saving both 
space and money. As a test, the mini- 
furnace is now being used to heat the 
laboratory where it was developed. 

oryx uses for food take in moisture from 
the air So by eating at night, the oryx 
can get enough water. Then, during the 
hottest part of the day, the oryx can re- 
duce the amount of heat its body pro- 
duces, saving water that it would other- 
wise lose by sweating. The oryx is also 
adapted so that its body temperature can 
rise more than 10 degrees above normal 
without harming the animal's brain. 

"From wonderland to waste- 
land" may become the story of Florida's 
Everglades National Park. The problem 
is familiar: the desires of people versus 
the needs of nature. The park is a wild- 
life refuge — one-and-a-half million acres 
of natural swamp containing a large vari- 
ety and abundance of plants and animals. 

The Everglades' very existence de- 
pends on a constant water supply from 
the north. For thousands of years water 
has come from an area beyond the park's 
boundaries. This area is now being 
drained for use in farming and building, 
as well as for a huge airport. "It took 
hundreds of thousands of years to cre- 
ate the Everglades," says Brooks Atkin- 



son, a writer for The New York Times. 
"Now men have the ability, facilities, 
and the will to destroy it in less than a 
century." 

Unidentified flying objects 

(UFOs) are nothing to worry about, ac- 
cording to a team of scientists headed by 
Dr. Edward U. Condon of the University 
of Colorado, at Boulder. The scientists 
recently completed a two-year study of 
the subject for the United States Air 
Force. More than 12,000 "sightings" of 
"flying objects" have been reported to the 
Air Force in the past 21 years. Dr. Con- 
don's committee investigated many of 
these reported "sightings," and found 
common explanations for most of them. 
While some remain unexplained, the sci- 
entists found no evidence strong enough 
to make them think that UFOs might be 
spacecraft from another world. They said 
there was no reason to believe that fur- 
ther investigation of UFOs would add 
anything to scientific knowledge. 

Several scientists have criticized the 
committee's work and conclusions. But a 
panel of scientists set up by the National 
Academy of Sciences to review the Con- 
don committee's report has approved of 
its methods and supported its conclu- 
sions. 

One of the "master chemicals" 

of life has been "manufactured" in the 
laboratory by two teams of scientists 
working separately. Scientists at Rocke- 
feller University, in New York City, and 
others at Merck Sharp & Dohme Re- 
search Laboratories, in Rahway, New 
Jersey, both succeeded in making ribo- 
nuclease, one of the enzymes in our 
bodies. 

Enzymes help our bodies to work in 
many ways. Some change the food we 
eat into substances that are needed for 
building our body cells; others change 
food into energy for muscle movement. 
Ribonuclease affects the way almost all 
of our body cells work. 

Because enzymes help control our 
body processes, they could be very useful 
in medicine. An enzyme called dextrin- 
ase, for example, has been reported to 
be helpful in fighting tooth decay. So far, 
though, enzymes have not been used 
very much in medical treatment, partly 
because scientists could not get enough 
of the enzyme needed. If enzymes can 
be produced in laboratories, it will help 
solve that problem. — R.J.L. 



14 



NATURE AND SCIENCE 




■ It is said that a forester once dreamed of a "perfect" tree 
—the stem was straight and did not taper, it had no limbs 
or bark, and it was square-sided. The forester must have 
smiled in his sleep, for the sight of acres of such trees 
would be a pleasant one— at least for lumbermen, carpen- 
ters, furniture makers, and others who work with lumber. 

The rest of us can be thankful that trees will never be 
like that. But trees are being changed by man. Farm crops 
and fruit trees have been improved so that they produce 
more and better food. And scientists are trying to develop 
trees that yield better lumber. 

This search for "better" trees is going on at the State 
University of New York College of Forestry, at Syracuse, 
and at other forest research centers throughout the world. 
Dr. Gerald R. Stairs is directing the tree improvement 
work at Syracuse. 

Taking eastern white pine as an example, Dr. Stairs 
explained, "We would like to develop faster-growing trees 
that are straight and self-pruning— that is, their lower limbs 
should die and drop off as the trees grow. The trees should 
be able to resist attacks by insects and diseases, and to grow 
well in a variety of climates. Finally, the trees should pro- 
duce high-quality wood that can be used in a variety of 
ways." 

The Search for "Superior" Trees 

To develop such trees, scientists at the College of For- 
estry begin by looking for healthy, straight, self-pruning 
trees in the wild. They take small samples of wood from 
these living trees. By examining and testing the samples, 
the scientists can select the fastest-growing trees with high- 
quality wood. 

The scientists then collect small branches from the tops 
of these special trees (called superior trees). These 
branches, which will grow seed-bearing cones, are col- 
lected either by climbing the trees or by shooting limbs off 
with a rifle (see Photos 1 and 2). 

The branches are then attached to other trees by a 

(Continued on the next page) 



Using a rifle with a telescopic sight, a scientist is able to shoot 
a small branch from the top of a 100-foot-tall pine. 




Tc graft a branchlet to a living tree, 
a slit is cut in a tree branch and 
the branchlet is put part-way into it 
(Photo 3). The two are then bound 
together (Photo 4) so that the 
branchlet receives food and can 
keep growing. 

Dream Trees (continued) 
method called grafting (see Photos 3 and 4). The scientists 
watch the growth of each grafted branch to see if it does 
a^ well as they expected. If so, seeds from the cones of the 
grafted branch are used to start growing a crop of young 
trees. The growth of these seedlings is also noted, and 
compared with the growth of seedlings from the seeds of 
"average" trees. In this way, the scientists are able to test 
the quality of the seeds and seedlings without waiting 40 
years or more for when the trees would be big enough to 
be used for lumber. 

Breeding Better Trees 

When the branches from the superior trees develop 
flowers, the scientists have another chance to produce 
trees that will yield better lumber. Usually the flowers of 
pine trees are pollinated by grains of pollen carried by the 
wind. However, by putting protective bags over the pine 
flowers, the scientists keep this from happening. They then 
pollinate the flowers (see Photo 5) with pollen grains they 




have selected. They might, for example, use pollen from 
one superior white pine tree to pollinate the flowers of 
another. Or they might use pollen from a Himalayan white 
pine to pollinate the flowers of an eastern white pine. The 
seeds that develop from the flowers will then produce trees 
that have characteristics of both parent trees. 

"We're definitely making headway," says Dr. Sfairs. 
Scientists at the College of Forestry have found Norway 
spruce trees that grow twice as fast as normal. The wood 
of these trees is also better for making paper than that of 
their slower-growing relatives. The scientists have also 
had success in developing white pine trees that are better 
able to resist a disease called blister rust. 

So far, the men studying white pine have been unable 
to produce trees that are "self-pruning," though they have 
grown trees that have smaller-than-normal limbs. If trees 
that quickly lose their dead lower limbs can be developed, 
much of the lumber from such trees will be free of knots 
(see Photo 6)— a woodworker's dream ■ 



A plastic bag put over pine flowers keeps pollen in the air 
from reaching them. The flowers can then be pollinated with 
pollen selected by scientists. Photo 5 shows pollen grains 
being forced inside the protective bag. 



The knots you see in the board on the right are the remains 
of limbs that died and stayed on the tree. When trees lose 
their dead lower limbs quickly, the result is more knot-free 
lumber, like the board on the left. 




Using This Issue . . . 

(continued from page 2T) 



uids (alcohol in water), or gases (air 
in water, carbon dioxide in soda pop). 
Gases can dissolve other gases, vapor- 
ized liquids, and certain solids. And 
some solids can dissolve certain liq- 
uids, gases, and other solids (sterling 
silver is a solution of copper in silver) . 
A chemist defines a solution as a ho- 
mogeneous (uniformly distributed) 
mixture of two or more substances 
whose amounts may vary. 

To go into solution, the particles of 
a substance must break up into mole- 
cules (the smallest particles of a sub- 
stance that retain all of its character- 
istics), or in some cases into pieces of 
molecules (called ions), before they 
can become distributed homogene- 
ously among the molecules of the sol- 
vent. 

When particles larger than the mole- 
cules of a particular solid are mixed 
evenly through a liquid or gas, the 
mixture is called a suspension. (Tiny 
particles of soil, sand, or clay are usu- 
ally suspended in river and ocean 
water; dust particles are usually sus- 
pended in the air.) A suspension can 
also be formed of two liquids that will 
not dissolve each other; this kind of 
mixture is called an emulsion. (You 
can make a temporary emulsion by 
shaking a spoonful of cooking oil into 
a jar of water. The oil breaks up into 
tiny drops spread through the water, 
but they soon rise to the surface and 
join together again. To make a perma- 
nent emulsion, mix some soap or de- 
tergent with the oil and water before 
shaking. The detergent helps the water 
molecules "stick" to the drops of oil 
and hold them in suspension.) 

• Is "homogenized" milk a solu- 
tion? Partly. Milk is mostly water with 
calcium and other chemicals dissolved 
in it and with butterfat suspended in 
it. Since butterfat is a liquid, milk is 
also an emulsion. "Homogenized" milk 
is treated to keep the drops of butterfat 
(cream) in suspension instead of ris- 
ing to the top as they do in "non- 
homogenized" milk. 

• Why are solutions vital to all liv- 
ing things? The cells that make up a 
plant or animal need a constant supply 



of food, which the cells change into 
energy and "building materials." The 
water entering a plant through its roots 
carries "food" dissolved out of the soil 
to the plant cells, then removes waste 
materials from the cells, in solution. 
An animal's body fluids, including 
blood, are mostly water. They carry 
food in solution from the animal's 
stomach to its cells, and carry wastes 
away for disposal. Fish get the oxygen 
they need to live from air that is dis- 
solved in the water. 

• Water is sometimes called "the 
universal solvent." Can you guess 
why? Water dissolves more substances 
than any other known solvent does. 
"Pure" water is almost impossible to 
find in nature; even rainwater usually 
has some air and impurities from the 
air dissolved in it. Water that passes 
over or through the ground dissolves 
many substances from the soil or 
rocks, often carrying them in solution 
to the oceans. 

Water will not dissolve oil or grease, 
though. A different solvent must be 
used to remove a grease spot from your 
clothes. Soap or a detergent emulsifies 
oil or grease (see above) so they can be 
washed away from greasy dishes. 

Activity 

Your pupils probably found that salt 
can be recovered from solution in 
water by letting the water evaporate. 
Can they think of a way to get pure 
water from a salt solution? (Boil the 
solution in an open pan and hold a cool 
pie tin above the pan. The water boils 
off as water vapor, leaving the salt be- 
hind, and the vapor cools when it 
touches the pan, forming drops of 
pure, distilled water. ) Can your pupils 
guess why this is an expensive way to 
get drinking water from the ocean for 
a whole city? (It takes a lot of fuel to 
distill enough water.) 

It's a Sonic Boom! 

To show your pupils how sound 
waves pile up in a shock wave around 
a plane flying at supersonic speed, 
move a stick through a pan of water 
(see diagrams). Moved slowly, the 
stick sets up waves that move out from 
it in all directions through the surface 



°.- u 'l )r 




' i i ! 



B 



water (A). Moved faster (B), the 
stick catches up with its waves and 
piles them up in a single V-shaped 
"shock" wave. Point out to your pupils 
that if the stick were a submarine 
traveling very fast underwater, its 
shock wave would take the form of a 
cone, just like the shock wave of com- 
pressed air that forms around a super- 
sonic plane (see diagram on page 4). 

You might explain to your pupils 
that the speed of sound through the air 
varies with the temperature of the air. 
(Cold air particles move slower than 
warm air particles, so they don't pass 
a wave of energy along to their neigh- 
boring particles as rapidly.) At high 
altitudes, the cold air reduces the speed 
of sound to between 600 and 700 miles 
per hour. The new SSTs are designed 
to fly about three times that fast. 

Dream Trees 

Plant breeding is becoming increas- 
ingly important as a means of improv- 
ing both the quantity and quality of 
wood and of wood pulp, used for mak- 
ing paper. Most people think of plant 
breeding only in relation to food 
plants, or to flowers. 

Hybrid corn is a classic example of 
what humans have achieved by breed- 
ing plants. Although corn had an an- 
cestor or ancestors among the wild 
grasses, there are no wild corns today. 
The corn we know is "man-made." 
Partly by trial and error, partly by de- 
sign, men have selected corn plants 
and bred them so that the resulting 
hybrid seeds would produce plants 
with characteristics of both parents. 

The first aim of plant breeders was 
simply to produce more corn per plant. 
In Illinois, an average acre of land 
produced 40 bushels of corn before 
the introduction of hybrid plants; now 
the average yield is 1 00 bushels. Pres- 
ent day hybrids have higher resistance 
to diseases and insects than the early 
(Continued on page 4T) 



March 17, 1969 



3T 



Using This Issue . . . 

(continued from page 3T) 

hybrids, and can be grown in colder 
climates. 

Using such hybrid plants and ferti- 
lizers, farmers in the United States and 
Canada have produced huge (but 
temporary) surpluses of food. Else- 
where in the world, however, plant 
breeders are engaged in a frantic effort 
to produce rice, wheat, and other 
grains to keep pace with the rapidly 
growing population. Their aim is to 
develop plants that produce more food 
of better quality; for example, rice that 
contains a greater amount of protein. 
Improved varieties of rice and wheat 
are already being grown in parts of 
Asia, but some food experts doubt that 
even this "green revolution" will be 
enough to prevent widespread food 
shortages and starvation during the 
1970s. 

For more information about repro- 
duction in plants and animals, see the 
March 27, 1967 issue of N&S. 



Brain-Boosters 

Mystery Photo. The sign painted on 
the road is intended for drivers, who 
view it at a slant from their cars. If you 
hold the picture sideways and at a slant 
(see diagram), you can see the sign as 



^rs. 




an approaching driver would see it; the 
letters will appear normal and the sign 
will be easier to read. 

Your pupils might enjoy looking for 
signs like this along the road, or trying 
to draw a similar sign themselves. 

What will happen if? If you have a 
sink in your classroom, you can dem- 
onstrate that water will squirt equally 
far from two (or more) holes at the 
same level in a tin can as it will from 
one hole. 

Point out that the weight of the 
water that is pushing water out of each 
hole is not the weight of all of the 
water in the can above the holes, but 
only the weight of a column of water 



having the same diameter as the hole 
and extending from the top of the hole 
to the surface of the water. So if the 
can is held level and each hole is the 
same distance from the top, the water 
pressure at each hole is the same. (Ask 
your pupils to guess which hole will 
squirt water farther if one hole is high- 
er than the other.) 

As long as the can is kept filled, the 
water pressure at each hole remains 
constant. If the can is allowed to drain, 
however, the pressure will decrease at 
each hole, squirting the water less and 
less far until the pressure drops to zero. 

Can you do it? Your pupils can use 
a straw or medicine dropper to add 
water very slowly to a glass that is al- 
ready brim-full. It is possible to make 
the water pile up a little higher than the 
sides of the glass. Surface tension (see 
"What Makes a Drop?", N&S, Oct. 14, 
1968, page 3T) holds the water to- 
gether and keeps it from spilling over 
the sides of the glass. 

Fun with numbers and shapes. Dis- 
tribute some toothpicks and let your 
pupils try to find a way to remove eight 
toothpicks from the design shown, 
leaving three squares. Here is a way to 
doit: 




Can your pupils find other ways to 
solve this problem? Can they make up 
similar problems of their own? 

For science experts only. Use the 
classroom globe to show to your pupils 
that if you kept going northwest as far 
as you could, you would travel in a 
spiral path until you reached the North 
Pole. 

Just for fun. When you have some 
time at the end of a day, let the chil- 
dren try to guess what will happen if 
they try the project suggested, basing 
their guesses on what they know about 
water, dishwashing liquid, food color- 
ing, and Alka-Seltzer, and the effects 
that some of them have on the others. 



After they have made their guesses, let 
them try it and see. What happens if 
they add food coloring of another color 
after the bubbles begin forming? 



Recent Books on Anthropology . . . 

(continued from page IT) 

remarks about the symbolism of par- 
ticular design motifs or about supersti- 
tions connected with the wearing of cer- 
tain garments, and wisely takes into 
account the modification of dress styles 
after the arrival of Europeans. The text 
is illustrated by many well-done line 
drawings of figures, details, and designs. 

Search for a Lost City: The Quest of 
Heinrich Schliemann, by Sam Elkin; 
illustrated by Lee Ames (G. P. Putnam's 
Sons, 94 pp., index, $3.49). This is a 
biography of the unorthodox nineteenth- 
century excavator of the ancient city of 
Troy. Told in a breathless journalistic 
style, the legend of the Trojan War 
springs to life and captures the reader's 
imagination as it must have Heinrich 
Schliemann's. His life is a study in con- 
tradiction: the shrewd businessman who 
is part romantic poet; the enthusiastic 
but naive archeologist who is scorned by 
scholars. Obsessed by the thought of 
discovering Troy, and taking Homer's 
Iliad as literal truth, Schliemann dug 
through numerous layers of the Trojan 
city and retrieved enormous treasure. 
Although he failed to understand much 
of what he discovered, and his methods 
were often unscientific, the story of 
Schliemann's dream-come-true is a fas- 
cinating interweaving of truth and fic- 
tion. 

Finding Out About the Past, by Mae 

Blacker Freeman (Random House, 76 
pp., $1.95). The best feature of this book 
is its inclusion of many fine photographs 
of archeologists at work and of the 
objects of their searches. The book is 
aimed at a very young audience (up to 
fifth grade, perhaps), but it does not 
spark the imagination as this subject 
might. The book describes ancient sites 
chosen more or less at random by the 
author, and tells about some of the 
treasures discovered. It then talks about 
the archeologist at work, dating and re- 
cording methods, and the preservation of 
recovered material. The account of an 
expedition lacks excitement; the reader 
is made aware of the things that are 
found, but feels no involvement with the 
people whose cultural remains are being 
uncovered. Also the author has failed 
to mention the importance of laboratory 
work — analyzing and cataloguing the 
collection's to make them intelligible and 
useful to other scholars. 



4T 



XAIl Rl l,\7) S< // \< / 



nature and science 

TEACHER'S EDITION 

VOL. 6 NO. 14 / MARCH 31, 1969 / SECTION 1 OF TWO SECTIONS 

COPYRIGHT © 1969 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 



"The City Stinks, Let's Clean It Up" 

by Gerald Schneider 



nature € 
and sciencfe 



■ Each child is a product of his hered- 
ity and environment. A person's bio- 
logical heritage is received through 
sperm and egg. His cultural heritage 
comes from tradition, social institu- 
tions, circumstances, and interaction 
with the physical environment. Small 
wonder that children raised in cities 
may grow up with little empathy or 
concern for wild nature. 

Gerald Schneider is Outdoor Program 
Specialist at the national headquarters of 
the Girl Scouts of the U.S.A., in New 
York City. 

WIDE WORLD PHOTOS 




Traditional teaching of nature and con- 
servation assumes that the pupils already 
value nature. But to city children whose 
environment is like this, a tree seems 
useless, a forest a frightening place. 



Nature study must seem trivial to 
most urban adults. They're probably 
preoccupied with problems of money, 
taxes, crime, and just getting to and 
from jobs each day. Conditioned for 
the worst, they often calmly tolerate 
smog, crowding, architectural ugliness, 
and other environmental evils. Their 
apathy is the bane of conservationists 
and others who are striving to pre- 
serve and improve man's environment. 

There's some hope for city youth, 
however. Even the slum child can 
learn to love nature and a healthy en- 
vironment. But to accomplish this, 
traditional approaches to nature and 
conservation education must be modi- 
fied. A child's cultural heritage must 
first include a recognition and love of 
nature and conservation in cities. 

Explore the Environment 

Awareness of environment is funda- 
mental. Many city children travel be- 
tween schoolroom and home televi- 
sions without seeing the land they pass 
through. They may be knowledgeable 
about Vietnam, black power, and such, 
but often don't realize that the air 
around them is polluted. Their en- 
vironmental awareness must be awak- 
ened. How? 

Focus on problems that affect their 
everyday lives: waste disposal, water 
supply, pollution, housing, parks. Let 
them probe the problems, study them 
firsthand, and suggest cures and solu- 
tions. 

Have them observe the environment 

of their neighborhoods or school areas. 

(Continued on page 4T) 




KgggfflllH 



IN THIS ISSUE 

(For classroom use of articles pre- 
ceded by m . see pages 2J-4T.) 

Challenge of the Cities 

A look at cities — their past growth, 
present problems, and future possi- 
bilities. 

The Quest for Inner Space 

How much living space is "enough"? 

How To Survive in the City 

A Wall Chart shows how certain 
plants and animals are adapted to 
"city life." 

The Pigeon Predicament 

A biologist may have found a way 
to reduce the numbers of these city 
birds by feeding them. 

Peeking at Pigeons 

Spring is an especially good time 
for your pupils to observe the be- 
havior of these birds. 

• A City Makes Its Own Climate 

How cities affect their own weather, 
and why this worries some scientists. 

• The "City Slicker" 

Your pupils can study cockroach 
behavior after learning how these 
insects get along in the city. 

• Brain-Boosters 



IN THE NEXT ISSUE 

Science Workshop investigations 
into birds' feeding habits, what 
makes plants bloom when they do, 
and the trajectories of falling ob- 
jects . . . How scientists are studying 
the dream process. 



USING THIS 

ISSUE OF 

NATURE AND SCIENCE 

IN YOUR 

CLASSROOM 



City Climate 

A modern city, or metropolitan 
area, is a gigantic monument to man's 
ability to change the natural environ- 
ment for his own purposes. But like 
most man-made changes to the natural 
environment, a city also changes the 
environment in ways that men have 
not foreseen — ways that make life in 
the city less pleasant and even harm- 
ful. Air and water pollution, over- 
crowding, noise, and traffic jams are a 
few of these undesirable changes in 
the environment. Hotter, cloudier, and 
wetter climates may be another, as the 
article on page 1 2 points out. 

Do your pupils think a city's ten- 
dency to change its own climate is as 
serious a problem as, say, the pollution 
of its air or the jamming of automobile 
traffic in its streets? Probably they 
don't. But if they think about what 
causes the city's climate to change, 
they will see that these problems are 
all related. For example, slowly mov- 
ing automobiles pour more heat and 



NATURE AND SCIENCE is published for The American 
Museum of Natural History by The Natural History 
Press, a division of Doubleday & Company, Inc., fort- 
nightly September, October, December through March; 
monthly November, April, May, July (special issue). 
Second Class postage paid at Garden City, N.Y. and at 
additional office. Copyright © 1969 The American 
Museum of Natural History. All Rights Reserved. Printed 
in U.S.A. Editorial Office: The American Museum of 
Natural History, Central Park West at 79th Street, 
New York, N.Y. 10024. 

SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester 
per pupil, $1.95 per school year (16 issues) in quanti- 
ties of 10 or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's 
edition $5.50 per school year. Single subscription per 
calendar year (17 issues) $3.75, two years $6. Single 
copy 30 cents. In CANADA $1.25 per semester per 
pupil, $2.15 per school year in quantities of 10 or more 
subscriptions to the same address. Teacher's Edition 
$6.30 per school year. Single subscriptions per cal- 
endar year $4.25, two years $7. ADDRESS SUBSCRIP- 
TION correspondence to.- NATURE AND SCIENCE, The 
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AND SCIENCE. The Natural History Press, Garden City, 
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hot gases into the air at a particular 
place than faster moving cars do, help- 
ing to pollute and heat the air, and thus 
affecting the weather there. 

The effect of a city on its climate 
may not seem very important now, 
especially to people who don't live in 
cities. Air and water pollution didn't 
seem very important, either, until 
scientists began to find that pollution 
affects people and all other living 
things, and that the effects of pollution 
are often felt far away from its source. 
And now that pollution has become 
bad enough to make us want to do 
something about it, we find that the 
job will cost billions of dollars and 
take a tremendous amount of work. 

Some scientists suspect that if cities 
keep growing in size and number with- 
out cutting down the amount of heat 
and other pollution they pour into the 
atmosphere, they could affect the cli- 
mate of the whole continent. So your 
pupils can see that the kind of climate 
a city makes for itself may be impor- 
tant to them, no matter where they live. 

Topics for Class Discussion 

• How is climate different from 
weather? "Weather" is a general word 
for the atmospheric conditions (air 
temperature and pressure, relative 
humidity, wind speed and direction, 
cloud cover, and precipitation) over 
a particular part of the earth's surface 
at a particular time. "Climate" is a 
general word for the kind of weather 
a place has over a long period of time. 

• Do the shapes and materials of 
natural areas of the earth's surface 
affect their own climates? Yes. A 
forest, desert, mountain range, or large 
body of water, for example, each helps 
to make its own climate. (The climate 
of an area also helps to make the shape 
and materials of the earth's surface 
there, through erosion by water and 
wind, for example, or by favoring the 
growth of vegetation.) The climate in 
a natural area may change, but usually 
very slowly, over thousands of years. 

• Has man begun only recently to 
affect his own climate? Ever since men 
began clearing forests to plant crops, 
and to build cities, he has been chang- 
ing the shape and materials at the 
earth's surface, and thus helping to 
make his own climate. The biggest 



change, however, began with the In- 
dustrial Revolution (see page 2), when 
men began to burn fuels to power ma- 
chinery, pouring heat, gases, and 
smoke particles into the atmosphere 
over cities at an ever-increasing rate. 
And as a city grows into a metropolis, 
it tends to change the climate over a 
wider and wider area. 

Activities 

• By holding one hand a few inches 
below a lighted incandescent light 
bulb, your pupils will find that their 
skin is warmed, just as it is by the sun's 
rays. If you use a clear bulb, they can 
see that the light, and apparently the 
heat, both come from the heated wire. 

Does the air carry heat from the 
filament to their hands? To find out, 
hold a sheet of glass or clear plastic 
between the bulb and hand. Their 
skin will still be warmed, but not the 
glass or plastic that separates the air 
next to the bulb from the air next to 
the hand. Using the other hand, they 
can test the air at the edges of the glass 
to make sure that heated air is not 
coming around it to their hand. This 
shows that whatever it is that carries 
"heat" from the filament (or the sun) 
passes through a transparent substance 
such as glass or the air without heating 
up the substance very much. 

• Have a pupil hold his hand near 
the bulb but shaded from it (see dia- 
gram), then close his eyes. Fold a sheet 




FOIL 



of aluminum foil several times to make 
it rigid, then reflect light from the bulb 
to the hand. Can the pupil tell from the 
warmth of his skin when "heat" is be- 
ing reflected from the foil? Have a 
pupil do the reflecting. Docs the bot- 
tom of the foil get warm when the rays 
are hitting it at a slant? How about 
when the foil is held so the rays fall 
straight down on it? This will demon- 
strate the heating effect of the sun's 
rays as they reach the earth at different 
(Continued on page 3T) 



2T 



NATURE AND SCIENCE 



NO. 14 / MARCH 31, 1969 



nature 
ind sciend 



SPECIAL-TOPIC ISSUE 
LIFE IN THE CITY 







:z- 




1F ' 



-I 



HOUR 

NETEfi 

PARKING 

PT SUN 



Chandeliers 

ILHiUiCid & TABLES 



— — — ■ 



J:A 



g=n : \ Lt 



i.-. 




nature and science 

VOL. 6 NO. 14 / MARCH 31, 1969 

CONTENTS 

2 Challenge of the Cities, by Laurence Pringle 

5 The Quest for Inner Space, 

by R. J. Lefkowitz 

8 How To Survive in the City, 

by Laurence Pringle 

1 The Pigeon Predicament, by Barbara Davis 

12 Peeking at Pigeons 

12 A City Makes Its Own Climate 

14 The "City Slicker," by Alice Gray 

16 Brain-Boosters, by David Webster 

Editor for this issue: Laurence P. Pringle 

PICTURE CREDITS: Cover, street scene and top circle, United Press Inter- 
national, bottom circle, George Resch, from Fundamental Photos; pp. 2-3, 
Photo Researchers. Inc.; pp. 4. 8-9, 12-16, drawings by Graphic Arts Depart- 
ment, The American Museum of Natural History; p. 4, photo by Bough, from 
Fundamental Photos; p. 5. Joan Whitney, from Black Star; p. 6. UPI; p. 7, 
top left. Wide World Photos, top right, UPI, bottom, Leo Vials, from Frederic 
Lewis; p. 10, artwork by Joseph M. Sedacca; pp. 10, 11, photos from The New 
York Times; p. 16, photo by David Webster. 



PUBLISHED FOR 

THE AMERICAN MUSEUM OF NATURAL HISTORY 

BY THE NATURAL HISTORY PRESS 

A DIVISION OF DOUBLEDAY & COMPANY, INC. 

editor-in-chief Franklyn K. Lauden; executive editor Laurence P. 
Pringle; associate editor R. J. Lefkowitz; assistant editors Mar- 
garet E. Bailey, Susan J. Wernert; editorial assistant Alison New- 
house; art director Joseph M. Sedacca; associate art director 
Donald B. Clausen • consulting editor Roy A. Gallant 

publisher James K. Page, Jr.; circulation director J. D. Broderick 
promotion director Elizabeth Connor 
subscription service Frank Burkholder 

NATIONAL BOARD OF EDITORS 

PAUL F. BRANDWEIN, CHAIRMAN, Dir. of Research, Center for Study of 
Instruction in the Sciences and Social Sciences, Harcourt, Brace & World, Inc. 
J. MYRON ATKIN, Co-Dir., Elementary-School Science Project, University of 
Illinois. THOMAS G. AYLESWORTH, Editor. Books for Young Readers, 
Doubleday & Company, Inc. DONALD BARR, Headmaster, The Dalton 
Schools, New York City. RAYMOND E. BARRETT, Dir. of Education. Oregon 
Museum of Science and Industry. MARY BLATT HARBECK. Science Teach- 
ing Center, University of Maryland. ELIZABETH HONE, Prof, of Education. 
San Fernando ( Calif.) State College. GERARD PIEL, Publisher. Scientific 
American. SAMUEL SCHENBERG, Dir. of Science, New York City Board of 
Education. WILLIAM P. SCHREINEtt, Coord, of Science, Parma (Ohio) City 
Schools. VIRGINIA SORENSON, Elementary Science Consultant, Dallas In- 
dependent School System. DAVID WEBSTER, Staff Teacher. Elementary 
Science Study, Education Development Center, Newton, Mass. • REPRE- 
SENTING THE AMERICAN MUSEUM OF NATURAL HISTORY: FRANK- 
LYN M. BRANLEY. Chmn., The American Museum-Hayden Planetarium. 
RICHARD S. CASEBEER. Chmn.. Dept. of Education. THOMAS D. NICH- 
OLSON, Deputy Dir., AMNH. GORDON R. REEKIE, Chmn., Dept. of Exhibi- 
tion and Graphic Arts. DONN E. ROSEN, Chmn., Dept. of Ichthyology. 
HARRY L. SHAPIRO, Curator of Physical Anthropology. 

NATURE AND SCIENCE is published for The American Museum of Natural History by 
The Natural History Press, a division of Doubleday & Company, Inc., fortnightly 
September, October, December through March, monthly November, April, May, July 
(special issue). Second Class postage paid at Garden City, NY. and at additional 
office. Copyright « 1969 The American Museum of Natural History. All Rights Re- 
served. Printed in U.S.A. Editorial Office: The American Museum of Natural History, 
Central Park West at 79th Street, New York, N.Y. 10024. 

SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester per pupil, $1.95 per school 
year (16 issues) in quantities of 10 or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's edition $5.50 per school year. 
Single subscription per calendar year (17 issues) $3.75, two years $6. Single copy 30 
cents. In CANADA $1.25 per semester per pupil, $2.15 per school year in quantities 
of 10 or more subscriptions to the same address. Teacher's Edition $6.30 per school 
year. Single subscriptions per calendar year $4.25, two years $7. ADDRESS SUB- 
SCRIPTION correspondence to: NATURE AND SCIENCE, The Natural History Press, 
Garden City, N.Y. 11530. Send notice of undelivered copies on Form 3579 to: 
NATURE AND SCIENCE, The Natural History Press, Garden City, N.Y. 11530. 




■ Suppose you had the job of planning and building a city. t\ 
How would you go about it? 

One thing is certain. There are probably no cities in $ 
the United States that you would want to use as an exact ■ 
model for your new city. Nearly everyone agrees that L 
today's cities are a mess. 

The air is polluted with wastes and noise; often nearby] m 
waters are polluted too. More and more highways are |( 
built — and then jammed with more and more automobiles.) % 
Those people who can afford to, usually escape to the; y 
suburbs. That leaves mostly poor people in the cities' cen- re 
ters. Taxes collected from these people don't provide 
enough money to solve all of the cities' troubles. 

This article tells about some of the problems of cities 
and some ways in which they might be solved. Other ar- 
ticles in this special issue tell about how crowding in cities) 
may affect people, how cities "make" their own climate, 
and about some of the living things that share cities with 
humans. 



h 



d 



» 



In the Beginning . . . 

Once there were no cities. Men lived in small, roving 
bands, or in villages. The first cities began about 5,500 
years ago, in what is now Iraq. Since then many cities 
have been born. Some have died, some have grown to great!) 
size. Still, for thousands of years only a small part of the 
world's population lived in cities. 

About 100 years ago, however, the proportion of the 
human population living in cities began to increase. The 

NATURE AND SCIENCE 



I 




automobiles have made it possible for suburbs to be built 
several miles from a city's center. But the differences be- 
tween "city" and "suburb" have become blurred as the 
suburbs closest to cities become more densely settled. 

The result is a new kind of human settlement — the me- 
tropolis (from the Greek words for "mother" and "city"), 
or metropolitan area. With people able to travel quickly 
several miles between home and work, the modern metrop- 
olis can be 100 times larger in area than the biggest cities 
that existed before the Industrial Revolution. 



by Laurence Pringle 



r ain reason for this great change was the Industrial Revo- 
tion. There were new sources of power, such as the steam 
igine. Men no longer had to depend mostly on their own 
uscles and those of other animals. Better farm machinery, 
;tter ways of raising crops and preserving foods, and 
:tter means of transportation meant that fewer people 
'ere needed on farms. Many people moved to cities, where 
l ey found jobs in factories. 

; This was the start of the industrial city. It began in Eng- 
r nd and has since spread all over the world. About one 
"iird of the earth's population now lives in or near such 
•ties. 

After the 1960 census, some people claimed that the 
-nited States had become "a nation of cities." The Census 
ureau reported that nearly 70 per cent of all Americans 
wed in city (urban) areas. 

By "urban," however, the Census Bureau meant any 
tttlement having more than 2,500 people. Actually, in 
960, nearly half of the United States population lived in 
nail towns or in rural areas. About 32 per cent of the 
opulation lived in cities of 50,000 people or more. An- 
other 21 per cent lived in suburbs around these cities, 
"ithough the 1970 census will probably show an increase 
■\ the urban share of the population, the United States is 
-ill far from being "a nation of cities." 
f Looking ahead, however, it seems that the urban share 
f the population will continue to increase. People are still 
saving farms to settle in or near cities. City dwellers are 
till moving to nearby suburbs. Modern highways and 

March 31, 1969 



Bigger Is Not Better 

A city usually grows by accident. It begins as a little 
village just like many others. But its location — beside a 
harbor, along a river or railroad route, near some cheap 
source of power — makes it an important center of trade or 
manufacturing. So a city grows, usually without any par- 
ticular plan. Even a city that was planned, such as Wash- 
ington, D.C., was designed long before the automobile 
was invented, and before surrounding suburbs made it a 
metropolis. 

The sprawling, unplanned growth of metropolitan areas 
is a source of many of their problems. Take the New York 
City metropolitan area for example. According to a group 
of city planners who studied it recently, the New York 
City region covers 6,900 square miles in three states. In 
1960, this metropolis had over 16 million residents. 

Within the New York metropolis there are 550 separate 
governments, including cities, towns, villages, and bor- 
oughs. Many of these communities have common prob- 
lems of water supply, pollution control, garbage disposal, 
parks, schools, and libraries. Problems such as these 
might be solved more easily and cheaply if the needs of 
the whole region were planned for. Instead, communities 
often tackle these problems by themselves. 

Even when communities work together, the troubles of 
the metropolitan area may get worse, not better. For 
example, the word "transportation" often seems to mean 
only "automobile" to government agencies in charge of 
planning for transportation needs of metropolitan areas. 
Many highways, bridges, and tunnels have been built to 
handle automobiles, while railroads and other mass transit 
systems have received little financial help. So rail service 
gets steadily worse. Some railroads that used to carry 
many commuters have gone out of business. And in the 
centers of many cities, automobiles are causing traffic 
jams, parking problems, and polluted air. 

People like the convenience of driving to and from 

work. One flaw in mass transit systems of buses, subways, 

or railroads is that they must follow fixed routes. In a 

sprawling metropolitan area, there are bound to be many 

(Continued on the next page) 



Challenge of the Cities (continued) 




The sounds of traffic and of continual building and repair- 
ing make cities noisy. So far, little is known about how the 
noise of cities affects the people living there. 



people who do not live along a mass transit route. These 
people often choose to drive their cars. 

A group of engineers at the Massachusetts Institute of 
Technology, in Cambridge, has a plan that could convince 
people to leave their cars at home— or not to have cars at 
all. A person wanting a ride would simply make a phone 
call, giving his address and destination. A computer would 
then send the information to the nearest "mini-bus," which 
would pick him up. These 10-passenger buses, run by elec- 
tricity, would each have a small territory to cover and no 
fixed route to follow. After picking up a few passengers, 
the buses would get onto an electric-powered "guideway" 
that would speed the buses downtown (see diagram). The 
M.I.T. engineers say that this system could provide the 



convenience of personal travel with the speed of mass 
transit. 

Such a system could be working in a metropolis by 
1975. But it probably won't be. The governments of a cen- 
tral city and of its surrounding suburbs would have to pro- 
vide great sums of money, and agree to spend it on mass 
transit instead of more highways for autos. There seems 
to be little chance of that happening. 

A Nice Place To Visit, But . . . 

During the next 30 years, the population of the United 
States may grow by 100 million people. And despite the 
dirt, noise, danger, and other unpleasantness of cities, 
most of those millions will live in metropolitan areas. The 
cities and their surroundings will change tremendously as 
homes, schools, factories, and other structures are built 
or replaced to meet the needs of the rising population. 

Will the resulting cities be better or worse places in 
which to live? Finding ways to make them better is a huge 
and costly job. Only in the past few years have scientists 
and engineers begun to really study ways of making cities 
more livable. There are still many questions to answer. 

What are the effects of air pollution and noise on peo- 
ple? When do street noises stop being just a background 
sound and begin to get on people's nerves? How much of 
a metropolis should be left as parkland and other open 
space? Should the outward growth of metropolitan areas 
be halted, and better use made of the space within the 
metropolis? How can housing be built for great numbers 
of people that will still give them quiet, private, living 
areas? 

Answering questions like these— and doing something 
about them— is the great challenge of the cities ■ 



W Look for these books about cities in your library or bookstore: 
Planning Our Town, by Martha Munzer, Alfred Knopf, New York, 
1964, $3.95; Under the City, by David Lavine, Doubleday & Com- 
pany, Inc., Garden City, New York, 1967, $3.50; Becoming a City, 

by Margaret Uroff, Harcourt, Brace & World, Inc., New York, 
1968, $3.75. 



In one plan designed to solve city traf- 
fic problems, people would be picked 
up at their homes (and returned) by 
electric "mini-buses" that would then 
travel downtown on an electric "guide- 
way." Individual electric cars could 
also use the "guideway." In the down- 
town area (right), people could also 
travel in capsules on tracks running 
along the fronts of buildings. 





Our attempts to reach to the moon and beyond 

may someday yield great benefits. But more 

important, perhaps, will be how 

successful we are in . . . 

The Quest 

for Inner 
Space 



by R. J. Lefkowitz 



■ A pale grey light filters through the window, 
and somewhere an alarm goes off. You yawn 
and start to roll over, but your kid brother is 
in the way. You roll the other way, and bump 
smack into a wall. You slide down off the bed 
and look out the window, but you can't really tell 
what kind of day it is because the brick wall of 
the building just a few feet away blocks out all 
the sunlight anyway. 

Downstairs, you bump and jostle your way 
through the crowded streets, then get into a bus 
with so many people already in it that it looks 
like a cartoon. But the squeezing and squashing 
aren't funny, and by the time you struggle your 
way to the door at your stop and shove your way 
through the throng of people waiting to get on, 
you feel so closed-in that you just want to 
scream. . . . 

Maybe you're lucky. Maybe you don't share 
a bed in a tiny room in a crowded apartment in 
a big, crowded city. Maybe you live in a nice 
roomy house in the country or in a suburb, sur- 
rounded by lots of trees and grass. But many 
people in the United States today live in cities. 
Some cities are less crowded than others, and 
some people live in less crowded parts of cities 
than others do. Still, there are millions of people 
in this country who often feel as though they 
just don't have enough "breathing space." 

Scientists, like many other people, are now 
wondering what effects too little space may 
have on people, and what can be done to give 
people the space they need. One way they have 
tried to find out is by studying the effects of 
crowding on other animals besides humans. 

Raging Rats and Dead Deer 

In 1947, a scientist named John Calhoun 
began a 14-year study of rats in an old stone 
barn near Rockville, Maryland. Dr. Calhoun 
wanted to find out what would happen to the 
rats if their numbers were allowed to increase 
while the rats were kept in a confined space. 

He found that as more rats were born, and 
the rat numbers increased in the pens he had 
built, the rats' behavior began to change. Fight- 
ing broke out among the male rats. The female 
rats either stopped bearing young or stopped 
caring for their young and building nests for 
them. Some of the adult males ate the young, 
even though there was other food available; and 
(Continued on the next page) 



March 31, 1969 



The Quest for Inner Space (continued) 
many rats died of disease. It seemed as though crowding 
had produced stress in the rats — a kind of "nervousness" 
that changed their behavior and made them less healthy. 

If Dr. Calhoun had let his experiments continue, the 
rat situation would probably have reached a "crisis," after 
which enough rats would have died of disease or from 
fighting so that the remaining rats could live normally. 

This sort of thing seems to have happened on James 
Island, a tiny piece of land in Chesapeake Bay, off Cam- 
bridge, Maryland. Four or five Sika deer had been brought 
to the island in 1916. There were no predators on the 
island to kill the deer, and by the late 1 950s the herd num- 
bered about 300. Then, from 1958 to 1960, nearly 200 
of the deer died. They hadn't starved to death, and there 
was no evidence that any disease had spread among them. 
It seemed that the deer numbers had been high enough to 
produce stress, which caused changes in the animals' 
bodies that killed the animals. 

No one knows whether crowding can have the same 
effects on humans as it has on some other animals. But 
many scientists believe that crowding in our cities may be 
making some people less healthy, or may be causing emo- 
tional problems in some people. Some scientists believe 
that high crime rates may be partly due to crowding, and 
that crowding may be one of the things that has helped to 
cause riots in our cities. Certainly crowding is helping to 
make a great many people unhappy. 

Of course, not everyone in a city feels so crowded. If a 
person has enough money, he can "buy" the space he needs 
in even the most crowded city. He can live in a large home 
or apartment, and can get from place to place in a private 
automobile, rather than on a crowded bus or train. Other 
people, however, are forced to live together in small spaces, 
where they are in constant contact with each other. 

You probably know yourself what it's like to be in a 
place where people keep bumping you. Imagine what it 
would be like to be in that situation nearly all the time, 
hardly ever having a chance to be alone. 

But do large numbers and small spaces always mean 
"crowding"? Perhaps not. When Dr. Calhoun was per- 
forming his experiments with rats, he found that about 150 
rats could live well together in a quarter-acre pen. But if 
the space were divided up into pens two feet square, it 
could hold 5,000 healthy rats in pairs. What seemed to 
matter most was not how much total space a rat had, but 
how much space "of its own" it had, where it could move 
around without bumping into another rat. 

Your Own Space 

People aren't rats, of course; but each of us seems to 
need a certain amount of space to call his own. It may be 
just a small "bubble" of space that separates us from other 




In many cities all over our nation, there are large 
families that can afford only one or two rooms in 
which to live. 



people as we go through our everyday activities, or it may 
be a room or a part of a room at home. Perhaps a city's 
apartment buildings could be built with these human needs 
more in mind. 

Years ago, apartment buildings were built one right next 
to another, with no space in between for trees and grass. 






Too Close for Comfort 

Do you have to be "elbow-to-elbow" with other people be- 
fore you feel "crowded"? Or do you begin to feel cramped 
even before another person comes close enough to touch 
you? People seem to need a "bubble of space" around 
themselves that keeps other people "at their distance." 
You probably can't measure your own "bubble of space," 
but you can try finding out how close you can get to another 
person before he or she begins to feel crowded. 

While you are having a conversation with a friend, take 
a small step forward. If your friend doesn't move, take an- 
other step toward him a few moments later. How many 
steps can you take in this way before your friend begins 
moving backward? What happens if you lower your voice, 
as though you were telling your friend a secret? Or if you 
raise your voice, as though you were talking to a large 
group of people? Does your friend change the distance 
between you according to the way you talk? Does a member 
of your family try to keep the same distance from you as 
your friend does? 

If you have some friends who come from other countries, 
you might try the experiment on them and see whether they 
behave the same way as people born in the United States. 
People from Germany and England, for example, tend to 
stand farther away from one another while talking than 
Americans do; Japanese and Arabs tend to stand closer 
together than Americans. Do you think that a person who 
was born in one country, but who lived a long time in an- 
other country where people "spaced themselves" differ- 
ently, would change the way he felt about spaces between 
people? Can you think of a way to find out? 




4v% 




\ I t 



■ 5*W 



Buildings like these (left photo) house many 
families, but often make people feel "closed- 
in" and "pushed-together." "Habitat," the 
experimental community built for Expo '67 
in Montreal, Canada, shows another way to 
house many families in a small area (top 
photo). The way that the apartments are 
fitted together gives each one its own ter- 
race, and makes people feel as though they 
have more privacy. 



Now many builders are using large land areas to put up 
tall buildings that often take up less than one fifth of the 
land. But people who live in the buildings often complain 
that the rooms are too small, the corridors too narrow, the 
ceilings too low. And the open space around the buildings 
is taken up by concrete walks and parking lots; or, where 
there is grass, it is often fenced off so that no one can walk 
or play on it. 

Perhaps a builder could buy a little less land, and use 
a little more of it for his buildings. With the money saved 
on land, he could build underground or rooftop parking 



lots, leaving more of the land available for recreation. And 
perhaps he could build thicker walls that would block out 
sound better, so that people wouldn't feel sometimes as 
though their neighbors were right in their own apartment. 
Many people believe that the problem of crowding can 
only get worse as more and more people pour into our 
cities. But that may or may not be true. We may not be 
able to stop people from moving into the cities, or from 
having children, but perhaps we can find ways of using 
space and building homes that won't crowd people, and 
that won't make people feel as crowded as they do now ■ 




A normal workday crowd in a big city. 



' 1 T/^F- 



\ ^^ ^^1 



nature and science wall chart March 31, 1969 



k How To Survive 
I in the City 

■ Whenever humans move into an area and build 
homes, towns, and cities, the wild animals begin 
to disappear. Their living places (habitats) are 
destroyed. In time, you might think there would 
be nothing but people — and their pets — living in 
the city world of concrete, close-packed buildings, 
and polluted air. 

If you look around in a city, though, you'll find 
many kinds of animals and plants living there. 
Some of them, like rats, have followed man and 
shared his living places for centuries. Others are 
species that once lived wild in the area where a 
city was built. All of these organisms have some 
characteristics that enable them to survive in 
cities. Some of them may live nowhere else. 

The drawings on this Wall Chart show some 
common plants and animals that live in North 
American cities. If you look in vacant lots and 
other open spaces in cities, you will find small 
plants such as dandelions, ragweeds, and plan- 
tains. Mammals such as raccoons and opossums 
often live at the edges of cities. See what other 
kinds of life you can discover in your city. 

— Laurence Pringle 



MAMMALS 



■ Bl 



BBS PI 
BEL! m 
III* 

EMK m 



mm 

■ S 



in 



=« 



TREES 



Fan-shaped leaves mark the ginkgo, 
another tree brought to North 
America from China. It is called a 
"living fossil," since it has been on 
earth for at least 100 million years, 
and has changed little in that time. 
It is able to resist most tree dis- 
eases and grows well along city 
streets. 





About 75 kinds of eucalyptus have been 
from Australia to California. They ha 
names as blue gum, red gum, and red i 
The leaves curl up on hot days, losi 
moisture to the air; the big taproot gra 
into the soil. In ways like these eucalypt 
do well with little water. 



The London plane tree is a hy- 
brid—a tree produced by 
breeding the American syca- 
more with the Oriental plane 
tree. It is better able to resist 
disease and to live in cities 
than either of its "parent" 
trees. 



Rats depend on people for most of 
their shelter and food, and people 
seldom disappoint them. Rats are 
wary, curious, and quick to learn. 
Traps and poisons may reduce their 
numbers, but they reproduce quick- 
ly and can survive as long as they 
find garbage and other wastes for 
food, and places to nest and hide. 



m*gm 



House mice can climb, jump, and 
swim well, and can survive on all 
sorts of food, including glue and 
soap. Females begin breeding when 
they are only 40 days old, and can 
have about six young a month. 





The ailanthus, or 
heaven, was first brd 
North America from ( 
1784. It grows quick 
most any kind of soil 
or shade, and thrives 
dust and waste gases 
air. Its seeds have ' 
that are twisted like i 
propellers; even a ligh 
carries them a long w 




<%Tn 



nnnnnz^ 




INSECTS 

and other arthropods 

Silverfish are quick-moving, 
scaly, gray insects, about a 
third of an inch long. They are 
active at night, and damage 
books, wallpaper, and clothes 
by eating glue, paste, and 
starch. 



I / 2 -l 1 / 2 "LONG 








LONG 



Like rats, cockroaches find 
the cities of man much to 
their liking. They hide in 
cracks and crevices by day, 
then come out and feed on 
garbage and unprotected food 
by night. They are quick-mov- 
ing insects, and have flat- 
tened bodies that can squeeze 
through small openings. 



The house centipede 
(not an insect) lives in 
damp places such as 
cellars. Its food is most- 
ly spiders and insects 
such as cockroaches. 





l'/ 2 -2"L0NG 



The cynthia moth was 
brought to North Amer- 
ica from Asia in 1861. 
Its caterpillars (larvae) 
prefer to eat the leaves 
of the ailanthus tree, so 
this big moth is found 
mostly in eastern cities 
where this tree grows. 




-s-£lZ^t 



W¥-& 



h 



BIRDS 



10" LONG 




Nighthawks are not hawks but resemble them as they fly in 
the evening sky above cities, catching flying insects. Out- 
side cities, they nest in open fields or on gravel. In cities 
they find the same sort of conditions on the rooftops of 
many buildings. 



The brown and red house finches 
are as common in some western 
cities as house sparrows are in 
the east. They eat the same kinds 
of food, and nest in bird houses 
and in crannies of buildings. 



6" LONG 



6" LONG 





Brought to North America 
from England in 1850, house 
sparrows now live in most 
cities of the continent. They 
are weaver finches, not spar- 
rows. They eat such food as 
grain and bread crumbs, and 
often compete for food with 
pigeons on sidewalks and in 
parks. 



Starlings were brought from 
Europe to New York City in 
1890. They have now spread 
over almost the entire United 
States. Starlings eat many 
kinds of food, and swarm by 
the thousands at city garbage 
dumps. Flocks of starlings 
roost on city buildings, espe- 
cially in the wintertime. To 
chase away these noisy flocks, 
city officials sometimes play 
recordings of a starling's dis- 
tress call. 





Pigeons raise young almost all 
year round in many cities. Peo- 
ple feed them grain and bread, 
and pigeons also find plant seeds 
in parks and crumbs on side- 
walks. Nests are built on window 
ledges of buildings. Because of 
their design, many new office 
buildings offer few nesting 
places for pigeons. 



Too many pigeons is the 
problem. Poisons and traps 
aren't the answer. And you 
can't get rid of all the roosting 
places. But a solution may 
have been found. 




the pigeon predicament 



BARBARA DAVIS 



■ Cities often have as many pigeons as people. And while 
there are those who like pigeons and want to feed and pro- 
tect them, other people are trying to get rid of them. 
Pigeons dirty streets and buildings. They may carry dis- 
eases that can spread to people. They annoy some people 
with their cooing and wing-flapping. 




This plastic owl was supposed to keep pigeons away from 
a New York City bridge by scaring them. It didn't work, for 
the pigeons weren't frightened at all. 



Health department officials have used one method after 
another to reduce the number of pigeons. One way is to 
use pinwheels or other objects that might frighten the 
birds {see photo) . But they do little good. The birds usual- 
ly get used to them, or else move to a nearby building. 

Poisons and traps have been tried, but people who like 
pigeons object to the killings. And poisons and traps may 
hurt other kinds of birds. Besides, as long as food and liv- 
ing space remain, other pigeons soon replace those that are 
killed. 

One sure way of reducing the numbers of an animal is 
to destroy the place where it lives (its habitat) . This works 
for some animals, such as mosquitoes that breed in 
swamps, but not for pigeons. It would be impossible to 
destroy all the pigeon-roosting places, from tenement 
buildings to the mighty heights of cathedrals. 

The pigeon problem is similar to those studied by wild- 
life biologists, who often have to try to increase or decrease 
the numbers of wild animals. And it is a wildlife biologist, 
Dr. William Elder, a Professor of Zoology at the University 
of Missouri, at Columbia, who may have found an answer 
to the pigeon predicament. 

Nuisance Numbers 

The ancestors of city pigeons lived on hills and cliffs 




near the Mediterranean Sea. Their gradual spread around 
the world has been the result of man's providing food and 
cliff-like buildings. Dr. Elder knew that many other birds, 
such as starlings, had increased to nuisance numbers be- 
cause man had made habitats for them. He wondered if 
some kind of birth control might be a good way of reducing 
the numbers of nuisance birds. Dr. Elder began to search 
for ways to stop birds from laying eggs, or to stop eggs 
from hatching. 

From reading about the work of other scientists, Dr. 
Elder learned of many chemicals that might control bird 
births. Some were substances that had been tried on ani- 
mals as part of the search for cures for the disease called 
cancer. These chemicals had lowered the animals' fertility, 
or ability to have young. Dr. Elder also learned that some 
insect-killing chemicals had affected the fertility of birds 
that ate the insects. He read of many other substances 
known to affect fertility. He hoped that out of all these 
chemicals, one would reduce bird births without killing the 
adult birds or making them sick. 

Success— in the Laboratory 

Dr. Elder began testing the effects of the chemicals on 
pigeons kept in laboratory cages. The pigeons were given 
food pellets that had been sprinkled with one or another of 
the chemicals. Some chemicals were given to pigeons for as 
few as seven days, others for as long as 50 days. After each 
tryout, the pigeons were given regular food pellets (without 
the chemicals added) for several months. During these 
months, Dr. Elder watched to see whether the chemical 
being tested prevented egg-laying, how long it worked, and 
whether it made pigeons sick. 

Some of the chemicals did nothing. Some made the birds 
weak. Others stopped the pigeons from laying eggs, but 
only while they were being fed the special pellets. 

After four years of tests, a chemical that had the right 
effects was found. Its manufacturer called it SC-12937. 
When fed to female pigeons for about two weeks, it 
stopped them from laying eggs for about six months. How 
SC-12937 works in the pigeon's body is still not known, 
but it may keep the pigeons from making egg yolk. 

Success— on Street Corners 

SC-12937 had succeeded in the laboratory. Next, in 
Missouri, a graduate student of Dr. Elder's counted the 
number of eggs laid by pigeons fed SC-12937. There, too, 
SC-12937 seemed to work. Fewer eggs were laid after the 
chemical was given, and those that were laid failed to hatch. 

The next step was to try the chemical on wild city 
pigeons. Dr. Elder supplied the food — wheat soaked in 
SC-12937. The American Society for the Prevention of 
Cruelty to Animals chose the testing sites — three New 

March 31, 1969 



York City street corners known to have large pigeon 
flocks. 

For 10 days in April (just after the breeding season had 
started) and 10 in September (near the end of the breed- 
ing season), grain with SC-12937 was scattered at two of 
the corners {see photo). The third spot received regular 
wheat. It was the control for the experiment — the normal 
condition with which the other sites could be compared. 

From May through December, the pigeons at each street 
corner were counted at least once a week. The people 
counting the birds also recorded how many pigeons were 
adults and how many were young. (Young pigeons, unlike 
the adults, have no white spots above their bills.) 

The total counts didn't tell much, for the numbers 
changed a lot just from day to day. But in December, 
there were fewer young pigeons than there had been at the 
beginning. The birds that had been young in May had be- 
come adults. Apparently, fewer pigeons had hatched. 



iitirnirr.^"! 




Dr. William Elder (in the light-colored coat) watches as wheat 
treated with SC-12937 is scattered at one of the New York 
City test sites. 

This birth control chemical is now being used in some 
European cities. But reducing pigeons by birth control 
chemicals alone is slow work. The chemicals only reduce 
the number of pigeons that are hatched and not the number 
of adults living when the chemicals are given. Pigeons 
usually live about five years, so waiting for the adult birds 
to die is a long wait. 

To reduce pigeon numbers quickly, Dr. Elder has sug- 
gested that first some adult pigeons might possibly be 
killed. Then, SC-12937 or another birth control chemical 
can be given several times a year, for several years, 
throughout an entire city. In this way, the numbers of 
pigeons can really be reduced ■ 

11 




Peeking at 
Pigeons 





The private lives of pigeons are a mystery to 

most of the people with whom they share a 

city's sidewalks. If you would like to learn more about 

these birds, here are some tips on things to watch for. 

• One way to get a close look at pigeons is to go where 
a flock comes to eat (or put out some grain or bread 
crumbs yourself, if there is no law against it in your city). 

Do the birds "fight" over the food? Do some 
individuals seem to be "bosses," always getting 
their way? What do pigeons eat that is not pro- 
vided by humans? Where do pigeons get water? 

• Pigeons make most of their cooing sounds during the 
mating season. You may hear them make other sounds, 
especially when they are frightened. Watch a male pigeon 
seek a female during the mating season. It usually doesn't 
recognize a female by sight, so it keeps approaching both 
males and females, cooing loudly. (The loud cooing helps 
to identify the pigeon as a male to other pigeons.) If the 
bird approached is another male, or a female that already 
has a mate, it drives off the male by pecking and beating 
its wings. When a male approaches a female that has no 
mate, the female usually just tries to edge away from the 
male. Watch to see paired birds "billing" — when the 
female puts her beak inside the open beak of the male to 
take some partly-digested food. 

• Where do pigeons build their nests? How high above 
the ground? What are the nests made of? (Field glasses 
might help here. Or try to find a pigeon that is building 
its nest and watch to see what materials it carries.) Do 
pigeons let other pigeons come near their nests? 

• During the long breeding season you may be able to 
see pigeons keeping their eggs warm, eggs hatching, and 
squabs (baby pigeons) growing up. Do the male and 
female birds share the job of sitting on the eggs? The eggs 
usually hatch in the morning, about 1 8 days after they arc 
laid. What happens to the broken shells? Watch the parents 
feeding the young. The adults "cough up" a partly-digested 
cheese-like substance, called "crop milk," which the young 
then take from the adults' beaks. When the squabs are 

older, the food they are given is not di- 
gested so much. The squabs are usually 
ready to leave the nest four weeks after 
hatching. You can watch them exercise 
their wings, and if you're lucky, you may 
see their first flight from the nest. 




■ The weather reports broadcast by big-city radio station 
remind us daily that a city is usually warmer than its si b 
urbs and the open country around it. Scientists who stud-ei 
the climates of cities in the United States and Englei 
found that a city also tends to have more cloudy da/s 
more fog, more precipitation (rain or snow), slower win Is 
and less sunshine than the countryside around it. 

The city itself causes these differences in climate, 
cording to Dr. William P. Lowry, an Assistant Professol 
of Biometeorology at Oregon State University, in Corvallid 
In Scientific American magazine, Dr. Lowry describe* 
how a city and the flat or gently rolling country around i 
produce such different climates. 



Heat from the Sun's Rays 

In the morning, Dr. Lowry pointed out, the sun's ray 
reach the city and the surrounding country at a low angl 
In the country, most of the rays are reflected from th 
ground back into the atmosphere, leaving very little hea 
in the soil (see Diagram /). Only the rays that strike th 







During most of the day, the sun's rays strike the earth 
at a slant. In the country, most rays are reflected 
..from the ground back into the air (Diagram 1). City 
walls reflect the rays to other walls and streets, which 
absorb heat from the rays (Diagram 2). 



later 
twei 
root 

wis 




"You can't do much about the weather," 

people often say. But scientists 

have found that building cities 

and living in them changes 

the weather quite a 

bit, because... 



MAKES ITS 



ides of trees and other plants leave much heat there. 

In the city, though, most of the sun's slanting rays strike 
ae sides of buildings, leaving some of their heat there and 
fien bouncing off toward other buildings or streets that 
re also heated by the rays (see Diagram 2 ) . The rock-like 
laterials that make up buildings and streets absorb, or 
oak up, heat much faster than soil does. The air gets most 
f its heat from contact with solid surfaces, not from the 
un's rays as they pass through the air. So the city air is 
/armed up faster than the country air. 

Around noon, when the sun's rays reach the earth at a 
teeper angle, the country ground absorbs more of their 
leat. The country and city have about the same tempera- 
lures then. Later, perhaps, rain will fall. In the city, the 
jvater quickly runs off the ground through drainpipes and 
ewers. In the country, most of the water stays on the 
;round or near its surface. As the water evaporates, it 
:ools both the land and the air. 

In the afternoon, the sun's slanting rays again warm 
|ihe city more than the countryside. As the sun sets, the 
country ground rapidly loses its heat to air that rises and 
'moves away as cooler air moves in to replace it. 

In the city, the first surfaces to cool off at night are 
;treets and rooftops. If many rooftops are at the same 
:evel, a layer of cool air may form over them and block 
I he warmer air near the ground from rising and moving 
iway. By dawn the city will probably still be four or five 
legrees warmer than the country around it. 

The Heat That People Make 

On a workday, the city's air is warmed even more by 



the heat, smoke, and gases from stoves, furnaces, cars, 
trucks, and buses. The center of the city becomes what 
weather scientists call a "heat island." The hot air from 
this area rises and spreads out over the whole city. 

The air from the heat island contains particles of dust 
and smoke that hang over the city and reflect light from 
the sun, making the sky appear hazy. At night, when the 
air cools, moisture from the air may collect on the parti- 
cles and form fog. 

Unless wind blows the particles away, or rain washes 
them out of the air, the haze gets denser each day. It cuts 
off some sunshine from the city, and people may burn 
more fuel to make up for the lost heat. This pours still 
more smoke, gases, and heat into the air. 

Dr. J. Murray Mitchell of the United States Weather 
Bureau wanted to be sure whether people's activities in 
cities affect the city's climate. Studying weather records, 
he found that a city will have a heat island whether it is 
located on flat or hilly land. He also found that a city is 
warmer on weekdays, when most people are working, than 
on Sundays. In addition, he found that as a city's popula- 
tion grows, so does the size of its heat island and the 
difference in temperature between the heat island and the 
areas around it. 

Today more and more people are moving from the 
country into our cities. The cities themselves are spreading 
out into the countryside around them. And in some places 
whole new cities are being built or planned. Weather 
scientists are wondering whether this will cause changes 
in the climate of our whole continent, and they are study- 
ing the climates of cities to find the answer ■ 




Some Things To Think About 






Some engineers have suggested that new cities be 
enclosed in a huge dome of plastic that would let the 
sun's rays pass through it, but not snow or rain. The 
engineers say that a dome two miles across could 
be built. 

Can you think of some things that would have to 
be changed to keep the air in such a domed city from 
getting too warm and polluted with exhaust gases 
and smoke particles? Might such changes improve 
a city's climate even if the city were not enclosed in 
a huge dome? 

If giant air conditioners could keep the air in such 
a domed city at a comfortable temperature and free 
of polluting gases and particles, do you think the 
city would change the climate of the country around 
it? Can you explain why? 



MALE AND FEMALE 
LOOK ALIKE 




THE **CITy 
SLICKER** 

Cockroaches like what people eat, so city life is 

right up their alley. These slippery insects 

roamed the earth before dinosaurs did, 

and they may outlast us all. 

by Alice Gray 



MALE AND FEMAL ■ 
LOOK ALIKE 



AUSTRALIAN 



■ If there is a city insect, it is the cockroach. Although it 
came originally from the tropics, the roach has traveled all 
over the world as a stowaway.lt even thrives in the Arctic 
(in heated buildings). Every large city swarms with 
roaches, and urban housewives usually aren't entirely free 
of them for very long. 

It is misleading to speak of "the roach," as though there 
were only one. In fact, there are about 3,500 kinds 
(species) in the world. Most of them are outdoor insects 
in the tropics. Only a few kinds of roaches live indoors. 
About half a dozen are at home throughout the continen- 
tal United States. (Alaska has only one species; Hawaii, 
being tropical, has many more species that do not occur on 
the mainland. ) 

International Insects 

The most widespread of these pests is the German 
roach, a pale tan species about half-an-inch long when 
fully grown. (Germans call this insect the French roach!) 
The American roach, a chestnut-brown species an inch- 
and-a-half long, is almost as common. The broad, dark 
brown, short-winged kind is called the oriental roach in the 
United States and the black beetle in England. (It is not 
really black, and not a beetle!) 

The Australian roach is like the American, but a little 
smaller, with a yellow streak on the "shoulder" of each 
front wing. The brown-banded roach resembles the Ger- 
man, but the female has short wings. The gray- brown 
Madeira roach is bigger than the American. It lives only 
in cities visited by ships from tropic ports. 

Although many roaches are named for places from 
which they supposedly came, the names may all be mis- 
taken. Possibly all the common house roaches began in 
Africa, but that is far from certain. They have lived with 
man so long and have been so widely spread in the belong- 
ings of traveling people that their original homes may 
never be known. The German roach may well have come 
from Asia before history began. Whatever their origin, 

14 




AMERICAN 



roaches have lived in cities as long as people have. Before 
that they shared the huts of villagers and the caves and 
tents of even earlier men. Not that they care much for 
people. They just like what people have to eat. 

Roaches, like people, are omnivores — eaters of both 
plant and animal food. But roaches eat a greater variety 
of foods than most humans. Plant or animal, living or dead 
— anything that will stand still and be eaten is food for 
roaches. However, they much prefer moist, soft substances, 
such as garbage. 

They drop their own wastes wherever they happen to 
be feeding. Many human diseases are caused by "germs" 
that can pass uninjured through the digestive system of a 
roach. The insects may spread infection by picking up 
"germs" in the sewer and leaving them in the kitchen. 
Polio and typhoid fever are among the diseases roaches 
may carry. However, no one has yet proved that roaches 
have ever played an important part in the sudden spread of 
any disease. 

Why Roaches Keep in Touch 

You have only to look at a cockroach to know that it 
lives in crevices. It is flat and slippery, with strong pushing 
spines on its legs and long, thread-like antennae that 
"smell" the outside world before the insect leaves its 
shelter. 

Roaches are thigmotactic — they can rest quietly only 
when in contact with something. The more surfaces of its 
body a roach has touching something, the more secure it 
seems to feel. House roaches hide by day in cellars and 
closets, behind and under articles of furniture, inside 
radios, electric clocks, and television sets, and in a thou- 



GERMAN 





sand crannies that a housekeeper never thinks to examine. 

At night they come out and search for supper and a 
drink of water. Roaches need a lot of water, unless their 
food is very wet. This is why they are so much more likely 
to be seen in the kitchen, bathroom, or laundry room than 
in a bedroom or living room. Because so many places offer 
shelter to roaches, it is very hard to reach all of them with 
an insect-killing poison (insecticide). 

Since roaches are so abundant, people think they repro- 
duce rapidly, but that is not true. Most species need at 



ORIENTAL 





least a year to produce a new generation of adults. The 

number of young produced by one female roach in her 

lifetime is not great when compared with many other kinds 

of insects. 

You may have seen a female roach with her egg capsule 

protruding from the rear of her body. The capsule looks 

like a tiny purse. Some species carry the capsule inside 

their bodies until the eggs hatch and the young are born 

alive. 

The young roaches look like adults, except that they 

have no wings. During their growth they shed their skins 

many times. Immediately after shedding, the insect is 

milk white. People who see 
a roach in a new skin are 
likely to mistake it for an 
albino — an animal that stays 
white all of its life, even 
though that is not the usual 
color for its species. But if 
you keep the roach for half a 

day, you will see it gradually change to the normal color. 
Even though most people dislike them, roaches are of a 

very old and distinguished family. Three hundred million 

years ago, they were the most common animals on land. 

They have changed very little since then. In the time of the 

dinosaurs, they were already as old as the dinosaurs 

would be now if they still 

existed. A family so tough 

and so adaptable is likely 

to be with us a while 

longer. Perhaps the last 

living creature on the 

earth will be a roach ■ 

March 31,1969 



FEMALE 





MALE 



Investigations with Cockroaches 

Cockroaches are good laboratory animals, easy to get 
and to care for, little enough to keep in a small space 
but large enough to handle and to watch without 
using a magnifying glass. (But be sure to get your 
parents' permission before bringing roaches into 
your home.) If you watch captive roaches carefully, 
you will see them doing things that will suggest ex- 
periments. For instance: 

• If there are hiding places in their cage, roaches 
will stay hidden all day and come out to feed at 
night. What happens if you keep the insects always 
in darkness or always in light? Do they stay on their 
usual schedule? If not, how long does it take for their 
schedule to break down, and how soon does it come 
back when you expose them to the normal cycle of 
light and darkness? If you find that the roaches stay 
on their usual schedule, see whether you can change 
their hours of hiding and hunting by changing the 
hours of light and darkness. 

• Roaches hide in dark crevices. Which is more 
important to the roach, the darkness or the tight fit? 
If you offer the insects a snug shelter made of trans- 



END MAY 
BE CLOSED 



lgE^» 



OPEN AT 
BOTH ENDS 



SNUG, TRANSPARENT SHELTER 



DARK, ROOMY SHELTER 



parent plastic, and a dark, roomy shelter that is 
round so that only the roaches' feet can touch any 
surface, which will they choose? 

• Does a roach have a special "home" to which 
it returns every morning? Give your roaches several 
identical hiding places, such as small boxes. Mark 
the insects with numbers painted oh their backs in 
waterproof ink so that you can tell them apart. Ex- 
amine each box every morning to see which roaches 
are in it. 

The better you get to know your roaches, the more 
questions you will ask yourself about them, and the 
more experiments you will be able to think of to help 
you answer your questions. 



Taking Care of Captive Roaches 

A gallon mayonnaise jar from a restaurant will make 
a fine cage for roaches. Cut out the center of the lid 
and put in a piece of wire screening, cut to fit. Give 
the insects a crushed paper towel in which to hide. 
Feed them dry cat food crushed to powder. Make 
them a drinking fountain out of a small, wide- 
mouthed bottle or test tube. (Just fill the bottle with 
water and plug it tightly with a wad of wet cotton, so 
that the water will not run out when you lay the bottle 
on its side. The roaches can squeeze the water out 
of the cotton when they need it.) 

For experiments that need space, a glass fish tank 
is good. It must have a tight screen cover. A band 
of vaseline about an inch wide just below the inside 
top edge of the tank will help to keep the roaches in. 



BROWN-BANDED 




prepared by DAVID WEBSTER -,* 



MYSTERY PHOTO What are these? 



WHAT WILL HAPPEN IF... 

. . . you let a glass of milk stand in your room for two 
weeks? You probably know that it will get sour. But 
what will it look like? Will it still be white? How else 
might it change? Try it and find out. Look at the milk 
every day to see what happens. You might try keep- 
ing it longer than two weeks to see if any more 
changes take place. 

» 

CAN YOU DO IT? 

If an egg is dropped into water it will sink. What can 
you do to make it float? 



FOR SCIENCE 
EXPERTS ONLY 

If the length of a piano 
string determines the pitch 
of the sound it makes, how 
can pianos of different 
sizes have the same notes? 




JUST FOR FUN 

Make a pinhole in a small piece 
of paper. Hold the paper about 
an inch from your eye, and look 
through the hole. At the same 
time, hold a pin by the point with 
your other hand so that the pin- 
head is between the. hole and 
your eye. If you move the pin up, 
it should look as though it is 
coming down from the top. 
Which way does the pin seem to 
go when it is moved from left to 
right? 



FUN WITH NUMBERS AND SHAPES 

What is the weight of a fish that 
weighs 10 pounds plus half its 
weight? 

Submitted by Helen Norton, 
South Harpswell, Maine 





ANSWERS TO BRAIN'BOOSTERS IN THE LAST ISSUE 



Mystery Photo: The sign painted on the road is usually viewed 
from a slant by the driver in a car. Hold the picture sideways and at 
a slant (see diagram), and the letters should look more normal. 




Can you do it? If you use a soda straw or 
medicine dropper to add water very slowly 
to a glass that is already hrim-full. you can 
make the water pile up a little higher than 
the sides of the glass. Can you guess why 
the water doesn't spill over? 



Fun with numbers and shapes: Here is a way to make 3 squares by 
taking away 8 toothpicks. 




For science experts only: If you kept going northwest as far as you 
could, you would travel in a spiral path until you reached the North 
Pole. 



What will happen if? Water from a filled tin can will squirt out just 
as far from two holes as it does from one. What would happen if 
you made three or four holes at the same level? 



Using This Issue . . . 

(continued from page 2T) 

angles throughout the day. 

• Have your pupils place directly 
beneath a lighted bulb a stone or piece 
of concrete of fairly even thickness, 
and a shallow glass or plastic bowl 
filled with earth to the same thickness 
as the stone. After half an hour or so, 
have them find out whether the bottom 
of the stone is warmer than the soil at 
the bottom of the dish. (They may be 
able to tell by touch; if thermometers 
are used, they should be shaded from 
the light.) Your pupils can tell that 
heat is conducted away from the sur- 
face of a rock-like material faster than 
from the surface of the soil. Could this 
explain why rock-like materials can 
hold more heat than unpaved ground 
does? 

• Putting one's hand in the air 
above a heated radiator demonstrates 
how the air gets heat from warm sur- 
faces (such as the earth, water, and 
city walls and streets that have ab- 
sorbed "heat" from the sun). 

• It might be well to explain that 
the sun (or the bulb filament) does 



not radiate heat, but certain waves of 
electromagnetic energy called infrared 
waves. These waves are longer than 
light waves, so we can't sec infrared 
"light"; but they are shorter than radio 
and television waves (see "Seeing 
Things in Different 'Lights' " and pre- 
ceding box, "Send Signals by Radio," 
N&S, March 18, 1968). 

Infrared waves, like light waves, 
pass through transparent substances 
and are reflected from the surface of 
opaque substances (especially from 
surfaces that are light -colored or 
shiny). But whenever they strike the 
tiny particles of substances called 
molecules, the infrared waves lose 
some of their energy to the molecules. 
This makes the molecules vibrate faster 
than before, which explains why the 
skin is heated by infrared waves that 
strike it (see "Exploring Heat and 
Cold," N&S, Nov. 1, 15, Dec. 6, 1965). 
The faster the molecules jump around, 
the more they bump into each other 
and lose some of their energy, which 
is radiated from the substance in the 
form of "new" infrared waves. These 
waves have less energy than the infra- 
red waves radiated by the sun, so they 



HOW TO TRAP COCKROACHES 



If your pupils want to try some of the 
investigations with cockroaches (on 
page 15), they may have some trouble 
catching these wary insects. They can 
make a roach trap like the one shown 
here, using a half-pint bottle with a 



SCREENING 




STAPLES 



BAIT 



screw cap. The best cap is the two-piece 
kind— a flat cover with a screw rim to 
hold it in place. You use only the rim. 
If you can't get that, cut most of the top 
out of an ordinary lid with a pair of tin- 
snips. You will also need a scrap of 
window screening about as big as half 
a sheet of letter paper, to make the 
funnel part of the trap. (Screening lets 
the smell of the bait in the trap reach 
the insects.) 

Roll a piece of paper into a cone. Fit 
the cone into the mouth of the bottle. 
Adjust it until the cone's point reaches 
about half way to the bottom of the 



bottle while the top fits the mouth 
tightly. Fasten the paper in this shape 
with sticky tape, then draw a pencil line 
around the cone at the top of the jar. 
Press the cone flat and cut it open along 
one fold. Trim the top about half an 
inch above the pencil line. Then use this 
pattern to cut your screening, with 
about half an inch extra at the side to 
allow for overlap. 

Roll the screen into a cone and fasten 
it with staples, or sew it shut with a big 
needle and a piece of string. Cut off the 
tip to make a hole big enough for a 
roach to get through. Fit the funnel into 
the jar and turn the very top down over 
the top of the jar. Screw on the cover 
to hold it in place. Bait your trap with a 
piece of very ripe banana or a little stale 
beer on a scrap of paper towel. Lay the 
trap on its side against a wall behind or 
under something in the cellar, or wher- 
ever you know that roaches live. (If you 
don't know where there are any, ask 
the manager of a supermarket or school 
cafeteria for permission to put the trap 
in a back room.) Leave it overnight. To 
care for the roaches you catch, see 
"Taking Care of Captive Roaches," on 
page 15. 



are more easily absorbed by other 
substances — even transparent sub- 
stances such as glass or air. 

Brain-Boosters 

Mystery Photo. The metal globes 
shown stockpiled in a Navy yard are 
used as floats for a mine net. 

What will happen if? When left at 
room temperature for a long period, 
milk will separate into a thick, white 
curd at the top of the container, and 
watery, clear whey at the bottom. The 
milk is decomposed by the action of 
microorganisms that are always pres- 
ent in the air. Encourage the children 
to find out what happens to other 
liquids when they are allowed to stand 
uncovered and out of the refrigerator. 
Fruit juices and soups are some liquids 
they could try. 

Can you do it? Adding salt to a 
glass of water will increase the water's 
density enough to enable it to float an 
egg, which is only slightly denser than 
water (see "How Dense Are You?", 
N&S, Sept. 30, 1968, pages 10 and 
2T). 

Can your pupils find other liquids 
that are dense enough to float an egg 
without having anything added to 
them? Can they find other substances 
besides salt that will make water dense 
enough to float an egg? Sugar, instant 
coffee, powdered milk, and soap are 
some substances they could try. 

Fun with numbers and shapes. Some 
of your pupils may try adding half of 
10 to 10 in order to solve this prob- 
lem; but this yields 15, which is not 
correct. The fish's weight is made up 
of half its weight plus half its weight. 
If a fish weighs 10 pounds plus half its 
weight, 10 pounds must be half the 
weight of the fish. The fish, then, must 
weigh 20 pounds. 

For science experts only. The pitch 
of a piano string is determined by its 
thickness, as well as by its length. A 
large piano has thinner strings than a 
small piano, in order to compensate 
for the greater length of the strings. 

Your pupils can test this by stretch- 
ing rubber bands of different thick- 
nesses to the same length and compar- 
ing the pitch of the sounds they make 
(Continued on page 4T) 



March 31, 1969 



3T 



Using This Issue . . . 

(continued from page 3T) 

when plucked. 

Just for fun. Distribute some pins 
and let your pupils try this. (Caution 
them to hold the pin head-up, and not 
to poke themselves in the eye.) When 
the pin is brought upwards, the head 
of the pin interrupts a light beam com- 
ing down from above (see diagram). In 



LIGHT 

like manner, each point along the shaft 
of the pin interrupts this beam first as 
you move the pin upwards, making it 
appear as though the pin is moving 
downward. (The pin is so close that 
your eye cannot focus on it.) 



"The City Stinks . . ." 

(continued from page IT) 

Is there enough parking space? Are 
more trash barrels and garbage cans 
needed on streets? Do buildings need 
repair? Does the air smell, or blanket 
everything with a layer of soot? What 
kind of plants and animals live in 
homes, vacant lots, parks, along 
streets? Encourage city children to 
take pictures of attractive and ugly 
spots in their community. Perhaps 
they'll want to develop a photo exhibit 
of contrasts to display in school or in 
the public library. 

Once accustomed to seeing their 
surroundings from a new perspective, 
they're likely to see how the city en- 
vironment affects them. A teenage girl 
said: "I'm seeing the city like it is for 
the first time." An eleven-year-old boy, 
after completing an environmental sur- 
vey, said: "The city stinks, let's clean 
it up." 

Get Them into Nature 

Fun and adventure in the outdoors 
is important. Love of nature and a 
healthy environment comes from favor- 
able experiences, not from speeches, 
sermons, or textbooks. Values are 
caught, not taught. 

Take a city nature hike. Visit stores, 
pet shops, parks, zoos, museums, fac- 

4T 



tories, waterfront areas, sewage treat- 
ment plants. Children can remove their 
shoes and socks in parks and feel the 
cool grass on their feet. Can they get 
permission to climb a tree? Is there a 
park pond where children can feed 
fish, ducks or geese? 

Outdoor activities for city youths 
are often best kept unstructured, light, 
and open-ended. The children will 
learn something on their own, and best 
of all, discover that nature has value 
for them. The fun of infrequent out- 
door experiences can be ruined by 
burdensome emphasis on fact mem- 
orization and note-taking. And words 
are no substitute for direct involve- 
ment with plants and animals. 

I once watched a university profes- 
sor lecture to a class of nine-year-olds 
in an arboretum. It was a rare trip out- 
doors for this inner-city group. The 
professor dryly explained the role of 
insects in flower fertilization, using a 
beautiful orchid as an example. Only 
a few children clustered around the 
professor could actually see what he 
was doing with the orchid. Others in 
the class stood around looking aim- 
lessly at the ground. 

Suddenly a girl in the class turned 
to her teacher and said: "Can we 
smell the flowers?" "Shh," replied the 
teacher, "the professor's talking. We 
can't waste time smelling flowers." 

How sad, I thought. The whole les- 
son was a waste of time for most of the 
children. If only they had smelled the 
flowers. Perhaps they might want to 
grow flowers in their drab classroom. 
Some children might have developed a 
love of flowers and returned to the 
arboretum to learn more about them. 
Instead, I overheard one youth saying 
to another as they left the arboretum: 
"Who gives a about flowers any- 
way." 

On another occasion, I watched a 
class of ninth-graders from the city 
visiting a nature center. It was also a 
rare chance for these children to get 
outdoors. Most of their time at the 
center, however, was spent indoors 
making leaf spatter-prints, viewing 
slides of birds, and listening to a lec- 
ture on the "web of life." They were 
completely listless and looked bored. 

Meanwhile, through the window, I 



could see a gray squirrel and two rob- 
ins on the lawn. A tiger swallowtail 
butterfly fluttered near a hedge. And 
the beginning of a self-guiding nature 
trail was visible and inviting. 

The class boarded a bus and left the 
center without having had any real 
outdoor contact. Worse yet — the cen- 
ter operates under federal funds pro- 
vided for "innovative and exemplary" 
outdoor education programs! 

Projects Can Help 

Love of nature and a healthy envi- 
ronment comes from meaningful in- 
volvement in projects to improve the 
living conditions of plants and animals 
in the city. 

Even simple bcautification projects, 
such as planting flower seeds and tend- 
ing them in flower boxes, have mean- 
ing. They can leave children with 
favorable impressions that lectures 
can't duplicate. 

The city child can plant shrubs near 
homes, around schools, and in parks 
(with permission). Shrubs are not only 
attractive in themselves, but provide 
food and cover for wildlife. Trees can 
be planted, also. They give shade, se- 
clusion, beauty, and protection from 
the wind. Birds and other animals may 
rest, nest, or roost in them. The affec- 
tion of children for shrubs, trees, or 
flowers they planted themselves is a 
wonderful thing. And it may carry over 
to nature at large, as children build and 
maintain animal feeding stations, bird- 
houses and birdbaths. You can seek 
advice on these projects from park de- 
partment officials, naturalists at a local 
museum, and conservation department 
employees. 

Beware of using the term "conserva- 
tion" too soon. It's difficult to get even 
experts to agree on what conservation 
means. You can study environmental 
problems without mentioning the ab- 
stract term "conservation." 

Once a city child is made aware of 
his environment and its problems, and 
has had opportunities for outdoor fun, 
he may be ready for more traditional 
nature and conservation teaching. But 
if the child hasn't first gained an ap- 
preciation of nature and its relation to 
his environment, your further efforts 
arc doomed ■ 

NATURE AND SCIENCE 



nature and science 

TEACHER'S EDITION 

VOL. 6 NO. 15 / APRIL 14, 1969 / SECTION 1 OF TWO SECTIONS 

COPYRIGHT © 1969 THE AMERICAN MUSEUM OF NATURAL HISTORY. ALL RIGHTS RESERVED. 



USING THIS ISSUE OF NATURE AND SCIENCE 
IN YOUR CLASSROOM 



Swinging Birds 

When people see a bird, tree, or 
other organism, their first question 
usually is: "What is it?" Today that 
question is usually easy to answer, 
thanks to an abundance of illustrated 
field guides that help identify all sorts 
of living and non-living things. 

There are two other questions that 
are much more important to ask, 
though, and not nearly so easy to an- 
swer. One is "What does it do?" Books 
and magazines give information about 
an animal's food, mating habits, and 
other characteristics. And knowledge 
about adaptations, such as the be- 
havior and bill size of birds mentioned 
in this article, answers part of the 
question "What does it do?" But a 
person must know quite a bit about 
nature in order to be aware of an or- 
ganism's role in its environment, and 
of how the creature affects and is af- 
fected by other organisms. This is the 
study of ecology, a science that has 
become critically important as humans 
learn how their actions are helping to 
destroy their own life-giving environ- 
ment. (See these articles in recent is- 
sues of N&S: "Tale of the Torrey Can- 
yon," Feb. 3, 1969; "A Whale of a 
Problem," March 17, 1969; "Chal- 
lenge of the Cities," March 31, 1969. 
Also see the Special-Topic issue, 
"Spaceship Earth," April 1, 1968.) 

"Big Bills, Little Bills," on page 4 



of this issue, attempts to answer 
another difficult question: "How did 
it get that way?" The answer, most 
scientists believe, is evolution through 
natural selection. 

About 100 years -ago Charles Dar- 
win and Alfred Wallace proposed the 
theory of natural selection. Darwin 
had studied and raised domestic ani- 
mals for many years. He knew that no 
two animals are exactly alike, even 
animals with the same parents. He 
also knew that animals could pass 
along their different characteristics to 
their offspring. A strain of animals 
with a certain characteristic— such as 
sheep with especially thick wool — 
could be developed by breeding only 
animals that had that characteristic. 

Reproduction is the key to natural 
selection, since anything that increases 
the chances of reproduction also in- 
creases the chance that a characteris- 
tic will be passed on to the next 
generation. 

When people think of natural selec- 
tion, they often picture a "struggle for 
existence," with the swiftest animals 
and the fastest-growing plants always 
succeeding and passing their charac- 
teristics on to future generations. 

But a plant or animal may be vig- 
orous and unusually successful in com- 
peting for food, space, or other needs, 
and still not be able to reproduce itself 
as well as other, less vigorous organ- 
(Continued on page 2T) 




IN THIS ISSUE 

(For classroom use of articles pre- 
ceeded by •, see pages 1T-4T.) 

• Mystery of the Swinging Birds 

Your pupils can investigate the feed- 
ing habits of birds. The article tells 
how these adaptations may have 
evolved through the process of 
natural selection. 

• Brain-Boosters 

Make Flowers Bloom 
When You Want Them 

By underexposing plants to light 
each day, your pupils can make 
them bloom early. 

Way-Out Ways to the Moon 

A cover and Wall Chart show how 
science-fiction writers of the past 
envisioned trips to the moon. 

• How High? How Far? 

With a marble and a simple ramp, 
your pupils can investigate the tra- 
jectories of objects moving through 
space. 

How Do We Dream? 

Scientists don't know yet, but this 
article tells how they are trying to 
find out. 



IN THE NEXT ISSUE 

Science Workshop investigations 
of shadows, insects that are active 
at night . . . Article and Wall Chart 
on biological controls . . . New theo- 
ries about dinosaur mobility . . . 
Index to Volume 6. 



Using This Issue . . . 

(continued from page IT) 

isms. Natural selection depends on the 
ability of organisms to produce off- 
spring. Only through successful repro- 
duction can characteristics such as 
swiftness be passed along. This fact 
helps account for the great variation 
in means of reproduction found among 
plants and animals. (This point is illus- 
trated in the N&S Wall Chart, "Six 
Ways to Success," advertised in N&S, 
Sept. 30, 1968, page 4T.) 

Evolution is going on all the time. 
Usually it takes thousands or millions 
of years for noticeable changes to take 
place. Sometimes, however, evolution- 
ary changes happen in a fairly short 
time, and we can actually see the re- 
sults. 

One example is the changes that 
often take place when a population of 
mosquitoes is sprayed with an insecti- 
cide such as DDT. Most of the mosqui- 
toes are killed when the area is first 
sprayed. A few survive — those indivi- 
duals that have the ability to resist 
DDT. They live to reproduce offspring 
that also are able to resist DDT. 
Eventually, if DDT is sprayed year 
after year, a new population of DDT- 
resistant mosquitoes will evolve. 
(Another example of rapid evolution 
is shown in the drawings on this page. ) 

Rapid evolutionary change like this 
is most likely to happen in a species 
having sexual reproduction, rather 
than asexual reproduction. The first 
life on earth, perhaps two billion years 
ago, probably had asexual reproduc- 



NATURE AND SCIENCE is published for The American 
Museum of Natural History by The Natural History 
Press, a division of Doubleday & Company, Inc., fort- 
nightly September, October, December through March; 
monthly November, April, May, July (special issue). 
Second Class postage paid at Garden City, N.Y. and at 
additional office. Copyright fo 1969 The American 
Museum of Natural History. All Rights Reserved. Printed 
in U.S.A. Editorial Office: The American Museum of 
Natural History, Central Park West at 79th Street, 
New York, N.Y. 10024. 



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per pupil, $1.95 per school year (16 issues) in quanti- 
ties of 10 or more subscriptions to the same address. 
Teacher's Edition with single subscription to student's 
edition $5.50 per school year. Single subscription per 
calendar year (17 issues) $3.75, two years $6. Single 
copy 30 cents. In CANADA $1.25 per semester per 
pupil, $2.15 per school year in quantities of 10 or more 
subscriptions to the same address. Teacher's Edition 
$6.30 per school year. Single subscriptions per cal- 
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TION correspondence to: NATURE AND SCIENCE, The 
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AND SCIENCE. The Natural History Press, Garden City, 
NY. 11530. 




ABOUT 1850 




TODAY 



Before 1850, most of the peppered moths near Manchester, England, were pale 
in color. Their speckled appearance concealed them from their enemies as they 
rested on light-colored tree trunks in the daytime. But as soot and smoke from 
industries coated the trees, the pale individuals were more easily seen than darker 
moths. Through natural selection the peppered moth became a dark species; today 
the pale forms are rare except in rural areas. 



tion. These one-celled organisms re- 
produced by fission — the division of 
their genetic and cellular materials— 
with each half becoming an individual 
of the same kind. In asexual reproduc- 
tion the offspring are identical "cop- 
ies" of the parent, unless a genetic 
change called a mutation occurs. 

Asexual reproduction is still com- 
mon in many groups of plants and ani- 
mals; some organisms have both 
sexual and asexual reproduction. The 
methods are similar in that a parent 
organism contributes a part of itself 
to a new individual. The main signifi- 
cance of sexual reproduction is that it 
promotes genetic variability. In sexual 
reproduction the offspring cannot be 
identical "copies" of their parents, be- 
cause the offspring have inherited 
characteristics from two different par- 
ents. Sexual reproduction maximizes 
variation in a species; asexual repro- 
duction keeps variation at a minimum. 
(For more information, see the special 
issue on reproduction, N&S, March 
27, 1967.) 



How High? How Far? 

By investigating the trajectories of 
marbles launched from a simple ramp, 
your pupils can find out that the path 
described by any object moving 



through space depends on: ( 1 ) its ini- 
tial speed and direction (velocity); (2) 
other forces applied to it in flight 
(rocket thrust or air resistance, for ex- 
ample); and (3) gravitational forces 
caused by nearness to other bodies. 

Since Galileo first investigated tra- 
jectories (with ramps and balls), 
knowledge of the subject has been 
used mainly for military purposes. 
You might point out to your pupils, 
however, that such knowledge is 
equally necessary for guiding a pro- 
jectile such as the Apollo spaceship 
into orbit around the earth or to the 
moon, and for plotting the path of a 
heavenly body, such as a comet. (Most 
scientific discoveries can be used for 
either constructive or destructive pur- 
poses; it depends on which purposes 
we consider more important.) 

Suggestions for Classroom Use 

Have your pupils do the first inves- 
tigation in the classroom, by simply 
rolling a marble off a desktop and re- 
leasing another marble at the height 
of the desktop as the rolled marble 
leaves the desktop. With a little prac- 
tice they can do this well enough to tell 
by the sound of impact that ( 1 ) both 
marbles travel through the same verti- 
cal distance in the same period of 
(Continued on page 3T ) 



NATURE AND SCIENCE 



VOL. 6 NO. 15 / APRIL 14, 1969 



ature 
and science 



Before going 
to bed tonight, 

seepage 13 

HOW DO WE DREAM? 




this as "far out" as the 
'AY-OUT WAYS TO THE MOON 
lown on page 8? 



nature and science 

VOL. 6 NO. 15 / APRIL 14, 1969 



CONTENTS 



2 Mystery of the Swinging Birds, 

by Martin A. Slessers 

5 Brain-Boosters, by David Webster 

6 Make Flowers Bloom When You Want Them, 

by Richard M. Klein 

8 Way-out Ways to the Moon, by Roger George 
1 How High? How Far?, by Robert Gardner 

12 What's New?, by B. J. Menges 

13 How Do We Dream?, by Margaret E. Bailey 



PICTURE CREDITS: Cover, pp. 8-9, Juan Barberis; pp. 2-3, Martin Slessers; 
pp. 4-7. 10-11, 14. drawings by Graphic Arts Department, The American Museum 
of Natural History; p. 5. photo by David Webster; p. 12, photos by Thomas 
Eisner; p. 13, Jerry Hecht, from National Institutes of Health; pp. 14-15, photos 
from The New York Times. 



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SENTING THE AMERICAN MUSEUM OF NATURAL HISTORY: FRANK- 
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RICHARD S. CASEBEER, Chmn . Dept. of Education THOMAS D. NICH- 
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HARRY L. SHAPIRO, Curator of Physical Anthropology. 

NATURE AND SCIENCE is published for The American Museum of Natural History by 
The Natural History Press, a division of Doubleday & Company, Inc., fortnightly 
September, October, December through March, monthly November, April, May, July 
(special issue). Second Class postage paid at Garden City, N.Y. and at additional 
office. Copyright © 1969 The American Museum of Natural History. All Rights Re- 
served. Printed in U.S.A. Editorial Office: The American Museum of Natural History, 
Central Park West at 79th Street, New York, N.Y. 10024. 

SUBSCRIPTION PRICES: In U.S.A. $1.15 per semester per pupil, $1.95 per school 
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of 10 or more subscriptions to the same address. Teacher's Edition $6.30 per school 
year. Single subscriptions per calendar year $4.25, two years $7. ADDRESS SUB- 
SCRIPTION correspondence to: NATURE AND SCIENCE, The Natural History Press, 
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NATURE AND SCIENCE. The Natural History Press, Garden City, N.Y. 1